I'm trying to recall a particular short, I believe it is with Shemp, where the following gag is introduced:
1. Moe tells a seated Shemp to rest his elbow on his knee, then rest his chin on his
hand (kinda like "The Thinker" sculpture)
2. Moe stomps on Shemp's foot
3. Shemp's involuntary reaction is to punch himself in the jaw!
I remember being convulsed by this years ago, but I've been unable to remember which short the gag was in. Now my sons (ages 10 and 12) are bugging me because they want to see the gag. Does anyone remember this?