if you really want to drive people up the wall, say “pardon the pun” but don’t make any puns. leave them guessing.
alternatively: compliment people on their great puns when they haven’t made any. they won’t ask what you’re talking about because they want to pretend it was on purpose, but they’ll also be deeply confused and forced to reanalyze their entire statements to look for the non-existent excellent pun.
also, you may want to start wearing a bulletproof vest if you do this often.