Transformers - When Timmy Turner wishes that the car becomes a robot, it is an obvious reference to the franchise. Also, the car he was riding was a "Hummer", which parodies the General Motors' character, Ironhide, that appears in the recent film.
Hulk Hogan - One of Timmy's bodyguards resembles Hulk Hogan.
People saying that certain people smell like cow butt.
Timmy saying, "I've got, like, 8 wishes left!" (ever since he was left with 8 wishes).
When Mr. Crocker shouts "Aah! I smell like cow butt!", the captions say A in place of LIKE, as in "Aah! I smell a cow butt"
Timmy supposedly uses his last wish to conjure up a robot, but when you count the wishes Timmy makes with the wand, he still has 4 wishes left; although, he may have made 2 more offscreen.