A lot of female cosplayers actually use makeup and (in some cases) paint on their butts. As do a lot of full-skin tone cosplayers. Typically not to make them look like boobs, but it's not entirely unusual. As a side note it looks like he painted a lot of his front as well.
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If you're asking if HE'S the one that painted his butt, that remains a mystery
G A M E
O V E R
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If you're asking if HE'S the one that painted his butt, that remains a mystery