One that comes to mind is in Monkey Island, which is a great and often extremely hilarious game, but some of the humor is pretty labored. And the worst example is Otis's line: "If there's one kind of piracy I don't like, it's CONSpiracy." Even in text form, it's such a forced non-pun, I mean piracy and conspiracy aren't pronounced even remotely the same way. Always hated that line.
I assume the entire idea behind that line is that it's supposed to sound awful.