The Cadbury Egg comes out Easter time, it is a chocolate egg filled with a creamey gooey center. Hence giving someone a Cadbury Egg Ass Kiss is the act of fucking someone, filling their ass with cum then planting a big kiss on their asshole afterward. Anyone can perform this on anyone and you don't have to wait for easter.
A type off ass on a woman which resembles sunny side up eggs jiggling on a plate. Also the type of shit you have after a long night of draft beer drinking.