My younger brother won't shut up about being better endowed?

Okay so, I'm 18 and my brother is 14. For some reason, he kept wanting to see how endowed we both were, he was very annoying about it so I said "Fine, let's get it over with". Well, it turned out he was better endowed than me, and now he won't shut up about it. He takes shots whenever he gets, what should I do to shut him up?
My younger brother won't shut up about being better endowed?
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