It's the subject of the matter, it's supposed to be a humorous gag, it can only be humorous in the correct situation.
Situational comedy requires something that's funny in the first place, just being there at the right time won't make it funny.
Everything requires a base to build from, if there is no base for something then that attribute cannot exist at all, the same way I can't fly under my own strength just because I'm above the ground (a little extreme of an example, but you get the point)