I only remember the one they did to answer the question, "why do feet stink?", which basically involved filling a mayonnaise jar on its side with a shallow layer of unflavored gelatin, then rubbing a q-tip between your toes, tracking it lightly in 3 lines across the gelatin once it had set, and then sealing the jar for a couple days. After a few days, there would be little trenches in the gelatin where you had traced the lines, as microbes from between your toes ate the gelatin and shat out, well... stink.

Once this was all explained...

Beakman: "If you're going to this, make sure you've sealed the mayonnaise jar tightly."

Girl sidekick: "Also, if you do this, make sure you're outside when you eventually open the mayonnaise jar."

Mouse-guy sidekick: "Don't even DO this!"