It started with a candid photo of people at a social gathering, with one person making a V hand gesture behind the head of the person next to them, much as in this photo of pro tennis players:
(#1) Swiss jock jokery: Stan Wawrinka doing the ‘bunny ears’ gesture behind Roger Federer
Bunny-earing someone is a prank (NOAD on the noun prank: ‘a practical joke or mischievous act’), pranks being a very culture-specific form of play + humor that deserve analytic attention that I’m not able to provide, but will just take as a cultural given here.
To come: a bit of the history of bunny-earing; senses of the expression bunny ears (illustrating (mostly metaphorical) sense developments in many directions); and uses of the V hand gesture (illustrating symbolic functions of many different kinds; the gesture itself is “just stuff”, without intrinsic meaning, which can be exploited for many different symbolic purposes). The act, the meanings of the linguistic expression for the act, the cultural significances (or “social meanings”) of the act.