Grumpy's guide to dealing with irritating colleagues, part 627..
"So Grump, what do you do when you aren't working here"
"Oh this and that"
"Are you a hitman? I could see you as a hitman.."
*Completely deadpan and without any hesitation* "It's funny you said that, I do know how to kill someone without leaving any evidence..."
Peace and quiet for the rest of the shift.