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No flies on me.

Awesome then!

Have you heard that saying before? Do you know the proper response

Not really. But I somehow think it means you are smart and quick :D

That made me curious, how to respond to it properly?

I say: No flies on me.
You say: They all shit and left.

Lol

Hahaha! Now that's something new learned!

Lol. Time to start throwing out a few tips.