It's a stupid thing to say. If I'm playing a game and a move I make turns out spectacularly well, I don't go around all the other players and say 'I'm sorry, I didn't mean to do something amazing. I meant to bore you with my mundanity; to let you, teammates, down, and to give you, opponents, a chance.'
No way. I was playing well, and I'm happy that something I wanted to go well did.
When conversing, if I make a pun that I didn't intend, why would I apologise or deny it? It's implicitly suggesting that humour is a bad thing. It's saying "I'm sorry that I said something funny and interesting at the same time. I really want just to be boring, so please treat me as such."
What a joke.