When you blow on someones stomach eliciting a loud farting sound.
Justin Timberlake, "I gave Timbaland the biggest zerbet last night. He seemed to really enjoy it."
The term "zerbet" was used by Bill Cosby in his role as Dr Heathcliff Huxtable in The Cosby Show i the 1980s to describe a "raspberry", his stage daugther Rudi had given him. A "raspberry" or "zerbet" is the act of putting one's lips against a body part, principally the belly, and blowing air. A tickling senstion ensues.
Rudi just gave me a Zerbet