What's the funniest slip-up you've heard someone else say?

Here’s my example!
During graduation, my principle announced that student so-and-so was joining the Marine Corpse. That scared me…she also said that someone won an apprenticeship, but I heard “a princess ship” and then spent the rest of the speech imagining what a princess ship would look like.
I suspect that these aren’t really slip-ups so much as it’s me not being able to understand her all of the time, which makes me feel a little bad…but it was really funny.
What funny slip-ups have you heard?