Peter invites his strict Catholic Mum for dinner at his flat where he's been "living in sin" with his secret girlfriend Joanne. Up to now, Peter has always passed Joanne off as a flatmate sharing the rent in order to avoid the wrath of his Mum.
During the dinner, his mother couldn't help but notice how attractive Joanne was. After some heavy hints from Mum, and sensing her suspicion, Peter said to his Mum:
"I know what you may be thinking, but I can assure you that I am single, celibate, and Joanne and I are merely flatmates".
About a week after the dinner, Peter realises his frying pan is missing. He writes to his Mum:
"Dear Mum, I'm not saying you took my frying pan, and I'm not saying you didn't. But the fact remains that it's been missing ever since you visited for dinner".
Several days later, Peter received an email from his Mum which read:
"Dear Peter. I'm not saying that you do sleep with Joanne, and I'm not saying that you don't. But the fact remains that if she was sleeping in her own bed, she'd have found the f**king frying pan by now".