No Time For Sergeants--one of the funniest movies ever.
The scene where he had all the commodes saluting was hysterical.
Interesting thing about the development of the Andy Griffith Show - the producers originally had envisioned Andy as being a goofball in the same manner he portrayed his character in No Time for Sergeants.
That apparently didn't work as well as they thought, so then they rewrote the character such that he's the mature, affable, but watchful sort that he became. As we all know, the goofball schtick was all Don Knotts.