Ian Somerhalder donating sweaty shirt

Ian Somerhalder and friend

Ian Somerhalder is donating his unwashed T-shirt to a lucky fan.

The Vampire Diaries star has partnered with activist outlet RYOT News to raise awareness for his Ian Somerhalder Foundation.

He shared a photograph of himself wearing the garb at a concert on Instagram Tuesday, begging fans to follow RYOT and IS on Twitter for a chance to win the item.

“Who wants the off of my back-this shirt that I’m wearing??? We’re picking tonight so make sure to follow @ryotnews & @IS_Foundation (on twitter) to win! Sorry it won’t be clean,but it saves water!” Ian mused.

The message sparked a fury among the actor’s lusty followers within minutes.

“Omg is the gun show in Heaven,” one fan wrote, referring to Ian’s muscular arm raised to the sky.

“I think I just pooped my pants,” another follower mused.

An employee from RYOT will select the lucky winner on Tuesday.

The 34-year-old hunk, who is currently filming upcoming flick The Anomaly with Alexis Knapp and Luke Hemsworth, is also very involved in charity work.

He founded the Ian Somerhalder Foundation in 2010 to “empower, educate and collaborate with people and projects to positively impact the planet and its creatures,” according to the organization’s website.

Ian recently revealed saving animals and the environment are his biggest passion.

“I’ve already collected more than six million dollars in donations to build a new animal shelter,” he told German magazine Bravo back in June.

“It’s so important to mobilize people, because they are our future.”

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