Why Do Actors Post Shirtless Pics?

To Prove Miracles Can Happen.
We know him as pudgy airhead Andy Dwyer on NBC's Parks and Recreation  but Chris Pratt posted evidence over the weekend that he can change.Big time.Six months no beer the 34-year-old actor wrote of
his pumped up physique.Kinda douchey to post this but my brother made me.Right Chris.We'll believe that. Pratt is in the shape of his life for the upcoming Marvel film "Guardians of the Galaxy.He also hit the gym for last year's Zero Dark Thirty.

 To Audition.
Zach Braff tweeted this pic with an open question to Channing Tatum asking to be considered for the sequel to Magic Mike.But was Braff serious?After all the normally scrawny 38-year-old actor-directorcrowdfunder does look like he's been hitting the gym.Show off!

To Show Patriotism.
Speaking of Tatum, he's never shy to take his shirt off. This time he posted a shirtless shot from his 2008 Iraq war film Stop Loss in honor of Independence Day (the day, not the movie!). Notice his patriotic tattoo!

To State the Obvious.
The Rock. Getting pumped.As if we needed evidence!? However, it does appear he has achieved the seeming impossible for his upcoming film Hercules: The Thracian Wars by getting EVEN bigger.

To Prove Total Submersion.
Tom Hanks recently toured the mighty USS Montpelier and has the shirtless pic to prove it... with hat!
Sometimes they're simply bored; sometimes they're making a joke; and other times they're proudly displaying the (pectoral) fruits of some hard labor at the gym. See why actors are into posting shirtless pics on social media.

To Show the Apple Doesn't Fall Far.
He's buff. He's acting.He's following his father Arnold Schwarzenegger's footsteps! Patrick Schwarzenegger 19 posted this morning pump pic just a month ago.He also appears in the upcoming comedy Grown Ups 2.

 To Dole Out Trainer Cred.
It's always good for a Hollywood It guy to hit the gym. In this case Shia LaBeouf lifted his shirt in honor of his trainer Peter Quillin (also pictured).