If you said, "I'm going to destroy this bowl of cereal," then I could say, "that would make you a cereal killer," and it would be a valid joke. (It still wouldn't be funny, but that's because it is the lamest pun of all time; please never use that joke.)
The point I'm getting at here is that comedy requires logic. A punchline requires a setup. The joke is based on having a premise which is true, but unexpected.
If somebody doesn't laugh at the next joke you make, it could be that they didn't get it, or it could be that there wasn't anything to actually get. Make sure your jokes make sense.