– What do you do with your tongue when you’re at the dentist?

– What do you mean – what do I do with my tongue when I’m at the dentist?

– Well, the dentist always tells me off because my tongue waggles about.  How do you stop it waggling and getting in the way?

– Oh, I just take mine out and put it in my pocket.

– Mum, you are such an idiot!