Parody is one of the few places where copyright law is actually on the comedian’s side. Here’s where the line sits.
In Campbell v. Acuff-Rose (1994), the 2 Live Crew “Pretty Woman” case, the Supreme Court held that parody can be fair use, even when it’s commercial. If your bit comments on or ridicules the work it borrows, the law gives you real room.
The catch: parody targets the thing it copies. Satire, borrowing a song or a scene to mock something else entirely (what I did when I was doing standup), gets far less protection. Courts care about that distinction a lot more than comics do, certainly more than I did back then.
Spoofing a song, a movie trailer, an ad? What you’re targeting may decide how much protection you have.