My all-time favourite gag in a Bob Clampett cartoon? When I was a kid, I could easily tell you. It’s when the Warners shield appeared out of nowhere with the Do-Do bird on it in Porky in Wackyland.
Note how it’s just a speck in the second frame below. In this third, if you blow it up, you can see it’s a mini-Warners shield.
And around it turns and it’s on to the next gag.
Norm McCabe and Izzy Ellis are the credited animators.