I have problems writing endings. Or at least funny endings. This may be universal. I don't know; I'm new at this.
Does one start with a punch line and work back or develop a funny
situation and riff?
Example: Protagonist with 'Police Clairvoyant' High Visibility Jacket
approaches Police Cordon. Officer on duty keeping back the looky-loos stops
him.
Protagonist: "Suits me. Sometimes the only way I get an afternoon off is to
turn up ten minutes before you call me."
Protagonist walks into a Novelty High-Vis Jacket Shop called "High Risibility Jackets" and asks for his money back. The shop assistant points him to a sign "Management accepts no responsibility for patrons not being funny."
Obviously, I'm over-thinking this, and projecting my condition onto the sketch. Either that or I'm just not funny.