1. slang To shake one's hand. He held up his hand waiting for me to slip him five, but I pretended like I didn't see it. The politicians huddled together with the corporate lobbyists in the corner of the conference hall, slipping each other five with little knowing winks and nods.

2. slang To slap hands with one in an informal show of celebration, congratulation, or friendship; to give one five. Hey man, what's up? Slip me five! The players stood in a row, slipping each of their teammates five as they ran past.