Best fanny Game
It's difficult to say what the "best" funny game would be, as different games will be more or less enjoyable depending on the group of people playing them. That being said, some classic party games that are generally well-received and can be quite humorous include:
"Never Have I Ever" - Players take turns stating something they have never done, and anyone who has done that thing must take a drink (or do some other designated action).
"Two Truths and a Lie" - Players take turns telling three statements about themselves, with two of the statements being true and one being a lie. The other players must try to guess which statement is the lie.