Inappropriate behaviour in front of OH's folks

[CalNaughtonJnr]

I drove my OH and her mother to London on Saturday and when we got to the capital I had cause to beep my horn at some douchebag in a pimped Range Rover who pulled out straight in front of me at a junction. Said douchebag then wound down his window and told me in no uncertain terms to go forth and multiply - somehow I was able to keep calm and simply laughed at him, however, had I been with anyone else I may have been tempted to fire some choice words back but it was a very close call and I'm sure would have made for a fairly tense atmosphere afterwards.

Have you ever come out with something extremely inappropriate in front of your OH's parents?