James Franco leaves many of his social media followers clueless to why he posts several selfies of himself half-naked.

But finally they get an explanation, and the 36 year-old actor also reiterated it is only for a bit of fun, and apparently "it's what the people want."

Franco defended his shirtless Instagram snaps to David Letterman while appearing on 'Late Night' this past Thursday (May 8th).

"What do you do?" Letterman asked the 'This Is The End' actor. "You take pictures of everything in your life?"

"There's a lot to get straight here and I don't even know if we have time," Franco stated. "But to me, it's just a fun thing. It's something I don't put a ton of thought into, but it gets a lot of attention."

The 66 year-old talk show host then probed Franco about a bizarre, and revealing, photo of himself with his hand down his underwear, which was shared last week.

"First of all let me just say there is not a person in this room who hasn't had their hand in their own pants," Letterman joking quipped.

"It's not like I'm putting that on billboards," the Oscar nominated actor replied. "Ostensibly, Instagram is for my fans. But now all the bloggers are following me on there so they'll just take it and use my images for whatever they want."

Watch Franco's appearance on 'Late Night' below

"But you will be the first to admit, looking objectively, it's provocative," Letterman said.

"I didn't ask you to look at it!" Franco said, before confidently adding, "It's what the people want!"

MORE: James Franco Deletes Suggestive 'Selfie'

"Why is it my fault" Letterman added. "I had nothing to do with this."

MORE: James Franco: Are His Recent Antics For Real, Or Are We Being Taken For A Ride?

"If you don't want to see it, don't follow me," Franco said. "Don't follow me on Instagram."