It's a long standing tradition in sports that as the new guys on the team, the rookies get more than their fare share of good-natured abuse from their more senior teammates. Sometimes it's little stuff - being voloun-told to clean up from practices and team events, having clear tape applied to the bottom of their skates, etc. - and sometimes it's in a form of friendly humiliation, like having your head shaved or being made to wear a sundress to a particular event! It is, for the most part, entirely harmless and usually engaged in to bring the individuals on the team closer together; growing their bond and furthering the very important cohesion of the squad.
Obviously, April 1st - April Fools Day - is an excellent opportunity to lay it on a little thicker and put everyone a little more on edge. There's something uniquely exciting about watching someone who believes that they're about to be pranked at any moment, but unsure of exactly when and what form the prank will take. It's like that moment of peak tension just before a band takes the stage at a concert: the entire crowd, going nuts for the last 5 minutes in a cacophony of shouts, cheers and screams, falls silent all at once in anticipation of the headline act. This moment is almost more rewarding than the prank itself, and when Toronto Raptors power forward Patrick Patterson decided to have a little holiday fun with T.O.'s rookies, the cameras were rolling to capture that magic moment for everyone!