Its when you go down on a girl while flapping your arms and screaching like a pterodactyl.
It could be, but not limited to taking the "cherry" of a girl who has not been eaten out before.
If this is her first time being eaten out, then you just cherrydactyled her pussy.
Person 1: Hey did you hear about tony eating out hillary's pussy last night?
Person 2: yeah dude, i heard he cherrydactyled her.
Person 1: no way man! i thought she's been eaten out before
Person 2: i guess not dude, he just swooped in and took it.