The lips are moving
A man walks into a bedroom and sees a hot, naked woman lying face-down on the bed. Q: What's his name? A: Willie Turner Q: What's name? A: Betty Will
His lips are moving.
Once when you tell it once when you tell her the punchline and once when she gets it.
Her teacher told her to go home and do an essay.
Their lips are moving.
Turn signals
About 1 in every 600 million has a chance of becoming a human.
Both should be changed regularly, and both for the same reason.