Snakes in a Hotel
Build a fake hotel bed that is entirely hollow.
Have it look like it's just a normal bed with sheets on the side and everything.
Fill the hollow bed with snakes (like in Indiana Jones: last crusade)
Rig the sheets on a pulley system to rip in the center and pull off to the side.
Create a fake prank for the contest winner so bam thinks that they are going to shoot a different prank the next day.
Either have bam lie on the bed with a piece of stunt glass or something along those lines and have it break by remote (possibly the remote control for the tv)
Have someone push/tackle Bam onto the bed into the snake pit.
The side of the bed will have plexi-glass pieces that can easily be pulled up creating a glass room for bam to be with the snakes in.
If you want to go the extra mile you could drop a box of mice in there with him.