The NFL is full of pranksters and jokers
(so is the MLB). Really it's men that play a serious game for a living filling in the boring times by acting like school boys and having some fun. In the 8 years I have played I have seen, experienced, and heard about some funny jokes that have been played on guys. Usually the jokes start out as simple humor but most always get escalated into elaborate retaliatory strikes that eventually will cross the line of good taste. Which leaves me to classify the pranks into three groups, the good, the bad, and the ugly.
link:
The Official Blog of Chris Cooley: Yode's Corner: The Practical Joke