Murr: Skydiving, Sharks (He's had to face both of these fears, as punishments for the show)
Q: Spiders (As a punishment, tarantulas were placed on Q's body while he was chained down)
Joe: I guess a bad donut :)
(The man isn't scared of anything)
Sal: The Common Cold, Sweat, Traffic, Strong Wind, Bugs, Germs, and Cats (He's had to come face to face with his fears multiple times on the show)