Seth Rogen stunned by co-star's Efron's perfect body

Pineapple Express star Seth Rogen couldn't keep his hands off his Neighbors co-star Zac Efron because he found his musclebound chest impossible to resist.

The funnyman quickly realised why Efron has a legion of lusty fans when he first took his shirt off for a scene in the comedy.

Rogen admits he was completely unprepared for his co-star's perfect form and had to keep rewriting scenes so he could reach out and touch the former High School Musical stud's torso.

He explains, "It's insane. It's freakish. The first time I saw him with no shirt on, my first instinct was there was something wrong with him... because he has so many bumps sticking out of his body. My body is, like, one big bump; his is, like, 87 different little bumps that come together. In the movie I make a joke; it's like his whole body is, like, a giant arrow that points to his d**k...

"He would, like, work-out between takes, which was, like, psychotic to me... He's like, 'It gives me energy and it makes my muscles pop out more'.

"We had to keep writing into the scenes that I, like, touched his body because I would just look at it and wanna just reach out and touch it as though it was a mirage of some sort. He's the sexiest mother f**ker alive."

And Rogen got a taste of Efron-mania when he sat through a screening of the film with fans.

He adds, "They (girls) make a noise I've literally never heard before in my life... I've been with my wife 10 years and I haven't even gotten one syllable of that sound... Guys make the noise, you hear it... I think it's coming from people's private parts, out their mouth."

The experience of working with Efron has given Rogen a sense that his pal spends his spare time just having sex: "I eat snacks, he just bangs ladies... If he's gone for more than 90 seconds, I assume he's having sex."