"Sooooo I'm on my period"
Works every time.
It'll probably work for you too! Especially if you're a guy.
As for fun things to do in conversation -
Stick your tongue out. Not at them, just poke it out and become fascinated by the only muscle in your body that is only attached at one end. It can take a while if you're in a group, but people will realise and give you funny looks.
Fake a phone call without your phone.
Pretend you're a spy and that what the person is saying is vitally important to your mission.
Replace every name and pronoun the other person says with "The raptors"
Begin staring intently at the speaker's left ear. If they notice, try to slap it.
Whenever someone looks away, remove an item of clothing, or undo a button. This one is really more of a challenge to see how nude you're willing to get in public/in front of the person, and how observant the surrounding people are.
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