etymologyslang
Growing up there was a friend of my family who would often use son of a gun as a slang term. For example,
And that son of a gun has a 300hp motor in it.
Like any father, my Dad wanted to raise me right, so he banned me from using the phrase. He implied that the phrase was synonymous with son of a bitch. However in more recent years I've often wondered: What is the origin of son of a gun, and does it really have anything to do with illicit relationships?
In the U.S., my son is usually used as a term of respect by an older person for a boy or younger man. There is an element of the speaker reminding the other of his/her seniority. If the two are close, it could be considered a term of endearment. The two don't have to be members of the same family.
I'm not sure how long it has been around, but I suspect a long time.
Is there really no equivalent in German?
Hype has a long history of slang use in the United States, with various meanings emerging and disappearing or changing shape. As a result, the source word for a particular sense of the term can be difficult to identify with any confidence. J.E. Lighter, The Random House Historical Dictionary of American Slang (1997) devotes the equivalent of two full-size dictionary pages to various forms of hype and hyper—and right out of the box it concedes that the meanings not directly related to the use of hypodermic needles "may reflect a different etymon."
As early as 1910, Lighter reports, hype (or hyp) appears as a short form of "hypodermic (needle)":
1910 Adventure (Nov.) 183: I turned to give another hyp. Ibid. 186: I was filling a hyp. with a new solution.
But Lighter also points out a number of other senses of hype that have emerged over the years: as a noun, a heroin or morphine addict (by 1924), a shortchange swindle or (any) con game (by 1925), a sudden steep but usually impermanent rise in retail price (by 1926), a misleading or exaggerated story (by 1938), and overblown publicity or advertising (by 1958); as an adjective, fraudulent (by 1978), and impressive or outstanding (by 1989); as a verb, to swindle or cheat (by 1914), to cajole or mislead (by 1938), (often as hype up) to inject via hypodermic needle (by 1938), (often as hype up) to make more exciting (by 1942), (often as hype up) to make more excited (by 1946), (often as hype up) to increase or inflate (by 1947), (in carnival cant) to charge more than the usual rate for merchandise (by 1950), and to promote aggressively (by 1959).
The term "shortchange swindle," by the way, refers to persuading a shopkeeper that one paid for some item with a larger-denomination bill than one actually handed over.
Etymologically, the main point of contention is whether all of the senses of hype ultimately come from hypodermic or whether one or more other words (most notably, hyperbole, though hypocrite is also a possibility) are the source of some of the senses involving deception or exaggeration. Two dictionaries—Harold Wentworth & Stuart Flexner, Dictionary of American Slang, first edition (1960), and Eric Partridge, Dictionary of Slang and Unconventional English, eighth edition (1984)—give hypodermic as the source of all meanings of hype. From Wentworth & Flexner:
hyped-up adj. Artificial, phony, as though produced by a hypodermic injection of a stimulant. 1950: "No fireworks [in this movie], no fake suspense, no hyped-up glamour." Billy Rose, synd[icated] newsp[aper] col[umn], Jan. 9.
From Partridge:
hype, n. Something intended to stimulate sales, etc.,; a publicity stunt; the person or thing promoted by such a stunt: s[lang, from] coll[oquial]: adopted, early 1970s ex US. [Citations omitted.] [Clarence] Barnhart [A Dictionary of New English (1973)] derives the term ex the US s[lang] for a 'hypodermic injection (especially of a narcotic drug)'.—2. 'Addict (from hypodermic) US' (Home Office) drugs world: 1970s.
hype, v. To stimulate by publicity stunts. [Citation omitted.] Ex the n. Also hype up.
On the other hand, Tony Thorne, The Dictionary of Contemporary Slang (1990), and Robert Hendrickson, The Facts on File Encyclopedia of Word and Phrase Origins, revised edition (1997), assert that the promotional senses of hype have their source in the word hyperbole. From Thorne:
hype vb, n (to create) excessive, overblown or misleading publicity. A term applied first to the activities of the pop music industry in the early 1970s, hype is a shortening of hyperbole. The word was apparently in use in the USA for many years among swindlers and tricksters before becoming part of commercial jargon (where it is now widespread).
From Hendrickson:
hype, hyperbole. Although there lived in the fourth century B.C. an Athenian demagogue named Hyperbolus given to exaggerated statement, hi name dos not give us the word hyperbole, or hype, as it is abbreviated today. Hyperbole derives from the Greek hyper, "over," plus bole, "throw," which conveys the idea of excess or exaggeration. Hyperbolus was just appropriately named.
Robert Chapman & Barbara Kipfer, Dictionary of American Slang, third edition. separates the hypodermic-based senses of hype from the senses whose origin is less definite:
hype1 1 n narcotics by 1913 A hypodermic needle; =HYPE-STICK 2 n narcotics by 1925 An injection of narcotics 3 n narcotics by 1924 An addict who injects narcotics: [citation omitted] 4 n A seller of narcotics: =CONNECTION: [citation omitted]
hype2 1 v by 1937 To blatantly promote: [citation omitted] 2 n Advertising or promotion, esp of a blatant sort: [citation omitted] 3 v by 1914 To trick, deceive,; originally to short-change 4 v by 1938 =HYPE UP ["To fake, manufacture; invent; =HOKE" or "To promote or advertise by blatant, obnoxious means" or "To give something a false impact, appeal, energy, etc."] {origin unknown; perhaps related to hyper, "hustle," of obscure origin, found from the mid-1800s; recent advertising and public relations senses probably influenced by hype1 as suggesting supernormal energy, excitement, etc., and by hyper2 and hyperbole; sense 4 supported by a 1914 glossary: "Hyper, current among money-changer. A flim-flammer"}
For reference, here is Chapman & Kipfer's entry for hyper2:
hyper2 1 adj by 1942 Overexcited; manic; over-wrought; =HYPED UP: [citations omitted] 2 adj by 1970s Exceeding most; very superior;: [citation omitted] {fr Greek hyper, "super," and in the first sense probably fr medical terms like hyperactive, hyperkinetic, hyperthyroid, etc; in some sources this term is associated with hipped and hippish, fr hypochondriac, "melancholic," first found in the early 18th century}
And finally John Ayto & John Simpson, The Oxford Dictionary of Modern Slang (1992), splits the hype entries into what it deems clearly hypodermic related and not clearly hypodermic related senses, but declines to hazard an opinion about the origin of the latter:
hype1 orig US noun Also hyp. 1 A drug addict. 1934–. [Citation omitted.] 2 A hypodermic needle or injection. 1929–. verb trans. 3 To stimulate (as if) by an injection of drugs; usu. followed by up; usu. as a past participial adjective 1938–. TIME [magazine] As he works, Mitchell has at times been so hyped up that Martha once asked his doctor to prescribe medication to slow him down (1973). {Abbreviation of hypodermic.}
hype2 orig US noun 1 dated An instance of short-changing, esp. done on purpose to deceive; someone who does this. 1926–. 2 Cheating; a trick. 1962–. [Citation omitted.] 3 Extravagant or intensive publicity promotion, 1967–. [Citation omitted.] verb trans. 4 To short-change, to cheat. 1926–. 5 To promote with extravagant publicity. 1968–. [Citation omitted.] {Origin unknown.}
Conclusion
Hypodermic is clearly the source word for the narcotics-related meanings of hype; but the origin or origins of the senses associated with deception, fraud, exaggeration, intensive promotion, and (as an adjective) manic or overexcited behavior remain very much in dispute.
Best Answer
The Phrase Finder writes that etymologists are at odds about where this phrase actually originated from. They write that there are two options:
There are sourced examples which support either of these hypotheses. For example, there is 19th century literature supporting the second option as well as 19th century examples supporting the first. Both options, however, lead to the conclusion that the phrase is a euphemism for son of a bitch.