Make your children laugh

I'm not much of a comedian. Mostly my children groan at my jokes and are constantly telling me I'm not funny.

Note: mum jokes are as (un)well received as dad jokes.

This doesn't stop me from trying to make my children laugh or play 'funny buggers' with them. For example here's a conversation I had with one of my children.

My child found a thermometer in it's clear plastic container, held it up to me and asked: 

Child: What does this do?

Me: It's a thermometer, it measures body temperature to see if people are unwell.

Child: How do you use it?

Me: You stick up someone's bottom.

Child: No you don't! You put in under the tongue?

Me: Oh no, poor dad.  I've been using it wrong all this time.

**

What are some funny jokes you tell your children?