The act of slapping your thumb with another person's thumb discreetly in order to avoid the embarrassing looks that are often associated with High-Fives.
Anna: I was so happy I really wanted to give him a High-five but I didn't want to make myself look like a fool in front of Eric.
Clay: Dude, you should have given him a thumb-five. No one would have known.
Clay: Dude, you should have given him a thumb-five. No one would have known.
by Thumbmaster November 23, 2009