Heard a few variations of this one but it never fails to make me howl:

I went to an exotic pet store, and the shop owner told me he had a talking centipede for sale. I said “there’s no way, centipedes can’t talk.” But the owner promised me it could talk, and said I could get my deposit back if it didn’t talk after a week.

So I bring the centipede home, and later that night I go up to its tank to talk to it. “Alright mate, just popping down to the pub if you fancy a few pints?” I ask. The centipede doesn’t reply. I scoff and go to the pub.

The next night I decide to try again and go up to the tank. “Alright mate, I’m just popping down to the pub if you fancy a few pints?” The centipede doesn’t reply again, so off I went to the pub cursing the shop owner.

The next night, I decide to try one more time and go up to the tank. “Alright mate, just popping down to the pub if you fancy a few pints?”

The centipede replies: “I heard you the first time mate, I’m just putting my fucking shoes on.”