Tonight’s Rangers starting pitcher, C.J. Wilson, is one of the most active Tweeters among baseball players. His Twitter feed (@str8edgeracer) is an entertaining one, and he has lately tried to start a new greeting phenomenon, called “upknucks.”
He calls the move, which is simply to bump knuckles with someone while the palm of the hand faces upward, "the new positive acknowledgment."
Here is an “upknucks” example he provided: