The entry for pig in the Oxford English Dictionary has an entry for the phrase, in a pig's eye:
colloq. (chiefly N. Amer. and Austral.). (in a) pig's eye (also ear, arse) : used as a derisive retort expressing emphatic disbelief, rejection, or denial.
The listed uses are:
1847 J. J. Oswandel Notes Mexican War (1885) iii. 163 Mr. Nicholas P. Trist‥is on his way to negotiate with the Mexican government to make peace. How are you peace—peace in a pig's eye.
1876 Oakland (Calif.) Daily Evening Tribune 17 Mar. 3/7 ‘Bought this mare for $16‥’. ‘In a pig's eye you've bought her for $16’.
1951 E. Lambert Twenty Thousand Thieves 322 ‘Pig's arse to that!’ another voice cried. ‘A jack-up—that's the shot.’
1968 W. Garner Deep, Deep Freeze ix. 110 ‘One stops short of probing the private lives of people for whom one has a regard.’ ‘In a pig's ear!’ she said vulgarly. ‘If duty called you'd have a man under the bed on my honeymoon.’
1992 O. S. Card Lost Boys (1993) vi. 154 ‘She must not have any idea of the effect of her words then’‥. ‘In a pig's eye.’
So the first recorded use was in 1847, and by this time the OED says that it was already being used as a "derisive retort". As the phrase is chiefly from North America and Australia, it is highly unlikely that this is Cockney rhyming slang. However, the article does say that "in a pig's arse" is an actual variant. One of the included uses (see 1951, E. Lambert) uses arse instead of eye.
Partridge
Partridge's A Dictionary of Slang and Unconventional English (2002) says:
into (a person) for (a sum of money), be. To owe a person so-much, to have let him down for a stated amount: Can, coll.: late C. 19-20. John Bearnes, Gateway, 1932, He's into me for ninety dollars, and I can't get a cent out of him.'
Where Can coll. is Canadian colloquial. The 2007 edition more simply says:
into preposition 1 in debt to, US, 1893
"... into me for ..."
Diving into Google Books, here's a possible 1902 from the American Ainslee's Magazine, Volume 10, Issues 1-6:
"Old man," confided Bill, after explaining the situation, "I need just a dollar and ten cents. Let me have it, like a good fellow." "But, Bill," replied Reece, hesitatingly, "you're into me for fifty dollars already."
And a definite 1903 from Arthur Morris Binstead's Pitcher in Paradise: Some Random Reminiscences, Sporting and Otherwise, published in London:
Two unplaced's an' one second, an' damme, she was into me for thirty-eight quid ! Stupid ? Aye, laad, even the bloomin' clerk rounded on me !
Here's a possible 1890 in Puck magazine which may be using a with a pun on the phrase:
"You 've got into me for all I 'm worth," remarked the Stocking to the Jumping-Jack. "All the same, I'm in a hole," replied the Jumping-Jack. And when Santa Claus heard them talking in that way, he broke the Jumping-Jack and took the ...
Walked and dribbled
Here's an interesting one from a possibly 1903 Pearson's Magazine:
He has dribbled into me for a thousand if he's had a cent, and now he must pay back by taking a chance.
Dribbling can also be found in the possibly 1917 Norsk-Engelsk Ordbog:
summer little sums ; cont driblets, petty sums. Cold has dribbled into me for a thousand ;
And finally, these two have walked into me for a [sum], which could be part of the same phrase.
Best Answer
Circle jerk?
(vulgar, slang, figuratively) Any group activity performed for personal gratification.
(Internet slang) An online community where a group of people form an echo chamber.
(echo chamber - an insular communication space that is of no interest to outsiders or refuses their input.)