A crotch itch; when your crotch itches and you announce "Chonnie!" to everyone around to warn them that you're scratching. Saying "chonnie" when you have a chonnie makes it acceptable to scratch.
Bri was walking when suddenly she yelled "chonnie" and started scratching.
Bri had a chonnie, so she announced to her friends, "Chonnie!" and the started scratching.
A flacid penis.
(ugly girl walks into the bar)
Tom: Oh man. She's totally giving me a chonnie.
(guy wusses out and refuses to do something)
Tom: Jesus, man. Quit being a chonnie.