I wasn't actually in the game where it happened, but the tale still regularly circulates about one of the DMs who had a Mimic in the form of a boat, tied up at the bank of an underground river. So the PCs find it, and hop in, and he says, "So, you get in the Mimic."
"What? No, we get in the... boat... "
"Like I said, so, you get in the Mimic!"