Have you ever been invited somewhere that you don’t really want to go, with someone you’d prefer not to go with? It’s perfectly acceptable to decline an invitation, but it can be awkward if someone you are not that into asks you out. You probably want to refuse the invitation without being too unkind.
If you are looking for a fun way to say no, where the person gets the hint and doesn’t invite you anywhere again without being too offended try one of our humorous comebacks. If you are lucky maybe they won’t invite you again in the future.