OK I'll start the ball rolling.
At a memorial service years ago I was introduced to the (then) Archbishop of Canterbury. It was freezing cold and he kept rubbing his legs, complaining that they suffered when it was cold. What I MEANT to say was either " you need some long johns" OR "you need some combinations".
What I blurted out was "you need some condoms"
I can laugh now but then I just wanted the floor to open up and swallow me