1. Their manager used to be so strict. Now he has lightened up a bit.
2. He can't take a joke without getting angry. He needs to lighten up.
3. She was just kidding! C'mon! Lighten up!
4. The police lightened up a little when they realized we weren't there to cause trouble.
5. He lightened up significantly once he got used to the work, the office, and his colleagues.
When people lighten up, they become less strict, they worry less, or they stop being angry.
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