Skip ahead to 8:35. You'll see it at 8:41.
Men In Black Part 1:
Thanks for the (bob o') link!
Y'know, in all the times I've watched Men in Black
over the years, I never noticed that!
Granted, it's Larry hitting Moe in the forehead with a backhand swing of his mallet, rather than a slap, but nevertheless! All I can say is, the boys were still in their shorts infancy, so the personalities/characters hadn't fully gelled yet.
Besides which, Men in Black
is a rather atypical short for Stooge behavior anyway -- I've always thought it more like a Marx Brothers skit than a Three Stooges short.
For duty and humanity,
JohnH aka QuinceHead