Did you hear about the guy who invented the “knock-knock” joke?

He won the “no-bell” prize.

More dad jokes you'll groan at

What do you call a fly with a sore throat? A hoarse fly.You can't trust atoms. They make up everything!Why is it bad to iron your four-leaf clover? Because you shouldn't press your luck.I ate a clock the other day. It was very time consuming.When is a door not a door? When it’s ajar.What should you do with a sick boat? Take it to the doc.