Showboating NBA referee Joey Crawford joined a long list of officials in various sports who have suffered injuries recently when he pulled up lame in the second quarter of today's Mavericks-Clippers game with what league officials are calling a knee injury.

Crawford is doubtful to return, and we're curious why this rash of referee illness and injury is occurring:

Ref Breaks Rib After Colliding With Maple Leafs Player, Hitting Ice

NHL Game Interrupted By Puking Referee

Camellia Bowl Official Injured By Object Thrown At Him By A Fan


Another Referee Knocked Out Of Game Due To Tip Injury

Hockey Fight Ends With Linesman Getting Punched In The Face


Basketball Referee Collapses After Tossing Opening Tip, Carted Off

Jameis Winston Somehow Got Away With Shoving An Official


Spanish Player Hits Referee, Himself In The Face With Basketball

Goalkeeper Tries To Rearrange Ref's Face With Haymaker


Lady Soccer Ref Gets Smoked In The Face By Rocketing Ball