give me/gimme (a) five
A request to give the speaker a "(high) five," that is, to slap their (usually) raised hand with one's own, as in a show of congratulation or celebration. "Five" refers to the hand's five fingers. "Gimme" is a colloquial form of "give me." I hear you aced your final exams! Give me five! Gimme give, kiddo!
ˌgive somebody ˈfive
(informal) hit the inside of somebody’s hand with the inside of your hand as a greeting or to celebrate a victory: Give me five!