Paddy and Murphy are in the pub one night, when Paddy turns to Murphy and asks why everyone keeps giving him sly grins when they look at him
"Well, Paddy, it's because of this. Last night, as we were all walking home from work; we looked in your front window and saw you banging the arse off your wife. We stood there for 10 minutes and saw the whole thing; everyone did."
Paddy, upon hearing this; bursts out laughing
"What are you laughing at?" Murphy asks "You've become a laughing stock because of this!"
"Oh, Murphy..." Paddy begins, struggling to hold back the laughter "The jokes on you! I wasn't even home last night!!"