Here's Mark Ruffalo's Nipple. It's For A Good Cause, And It's Mark Ruffalo's Nipple.

Just in the nip of time.

This takes going topless to a much-needed level.

Mark Ruffalo tweeted a photo of his bare and rather modestly-sized nipple this week. His reason goes beyond just showing off his shirtless style.

Ruffalo's nipple photo is part of a campaign for One For The Boys, an initiative that seeks to eliminate myths and bring awareness to men's cancer. Male breast cancer in particular is rare, for example, but lack of awareness is a serious problem as it leads to delays in getting diagnosed that affect men's survival rates.

Ruffalo and other guys bared their nipples this week for this very worthy cause, and you can too.

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Art History With Male Nipples