Wet Billy

To orally lubricate one's own finger with saliva and insert into another person's anus. Similar to a Wet Willy, but in the B-hole.

Rob gave Scott a Wet Billy.

Wet billy

Wet Billy is when you kick you're finger and shove it up someone's ass.

Person 1 . Man we we're having sex and she gave me a wet billy!
Person 2 . Wet Billy?
Person 1. Yeah she shoved her slobber fingers up my asss