AceShowbiz - Justin Long was left red-faced filming a full-frontal scene with Christina Applegate in new movie "Going the Distance" because he had a crush on the actress as a child. The actor, who plays the love interest of real-life on/off girlfriend Drew Barrymore in the romantic comedy, accidentally bared his manhood during one scene with the blonde star.

And director Nanette Burstein liked Applegate's shock reaction so much she asked him to reenact the take, before she eventually cut it from the film. He explains, "There was one scene where I go up to surprise Drew... Applegate comes around the corner, catches me in a towel... During one take... I gestured with my hand that was holding the towel to the upstairs bathroom, drop the towel, and so my boys were out there."

But Long will never forget the horror of going full-frontal for a day on set with Applegate, who played his childhood crush Kelly Bundy on hit U.S. 90s TV series "Married with Children". He adds, "We had to turn the camera around to Christina - to get her reaction."

"So generous giving actor that I am, I had to do exactly what I did again. And I grew up watching - who didn't have a crush on Christina, on Kelly Bundy? It was one of those surreal (moments). I found myself for a solid hour of my life showing her my c**k and b**ls."