Learn English – Etymology, ubiquity and synonyms of the phrase “Tribal Knowledge”

Both Wiktionary and Etymonline say that the origin of lark in the meaning "frolic, prank" is not clear. Wiktionary puts it like this:

Origin uncertain, either

• from (notably northern) English dialect lake/laik (“to play”) (c.1300, from Old Norse leika (“to play (as opposed to work)”)), with intrusive -r- common in southern British dialect; or
• shortening of skylark (1809), sailors' slang, "play roughly in the rigging of a ship", because the common European larks were proverbial for high-flying; Dutch has a similar idea in speelvogel (“playbird, a person of markedly playful nature”).

There are a few theories, that's for sure. But the bottom line is, the etymology is unknown. I won't leave you without these pointers, though:

• The Phrase Finder:

  This is an interesting phrase in that, although there's no definitive origin, there is a likely derivation. [...] The fact that [Jonathan] Swift had alluded to the streets flowing with dead cats and dogs some years earlier and [in 1738] used 'rain cats and dogs' explicitly is good evidence that poor sanitation was the source of the phrase as we now use it.

• Wikipedia:

  The English idiom "it is raining cats and dogs", used to describe an especially heavy rain, is of unknown etymology [...] There may not be a logical explanation; the phrase may have been used just for its nonsensical humor value[.]