MMA Fighter Beats Up A Public Sex Offender

She kicked his butt!

Not all heroes wear capes . . . but there are times that a raincoat would help identify the bad guy.

A Brazilian MMA fighter named JOYCE VIEIRA was doing a swimsuit photo shoot on a beach in Rio earlier this month when she saw a dude nearby watching.

She quickly realized he wasn't just watching . . . (Careful) . . . He had his equipment out and he was working it vigorously.  She told him to stop, and he said, quote, "Why, you don't like it?  Come here."

Well, that was the wrong answer.  Joyce kicked him, he punched her back . . . and then she REALLY got mad.  She set upon him like a tornado made of feet, fists, elbows and teeth.

He started screaming, and when someone else came to help, he ran away.  The photographer got some pictures though, so police were able to find and arrest him. Plus we can see 'em too... and that's what matters.