via i.cdn.turner.com

"It was not Jerome Boger's intent to exchange a high-five with the player," a league spokesman told the paper. "As Vince Young took a knee on the game's final play, Jerome Boger jogged in with his right arm in the air to signify the play was over. That is the proper administrative signal for the referee.

"As Young turned around, he saw Boger approaching the line of scrimmage with his arm raised. As Boger moved toward the line of scrimmage, he started to bring his arm down. However, before he lowered his arm, Young, moving towards the referee, raised his own arm and the two exchanged what appeared to be a quick high-five."

http://profootballtalk.nbcsports.com/2009/11/25/nfl-says-ref-didnt-give-vince-young-a-high-five/

So I guess by those standards a chest bump isnt really a chest bump either, its just two guys who happen to be in the air at the same time trying to occupy the same space. /sarcasm