Paul Rudd tried ruining a This Is 40 scene out of fear it would upset a Friends co-star

Paul Rudd once tried to ruin a scene in a hilarious comedy film out of fear he would upset a close friend.

This is 40 is a fairly blunt and confronting look at what middle-aged married life with two kids can look like.

The 2012 movie stars Paul Rudd and Leslie Mann as they try to navigate their lives as they get stuck in a bit of a rut.

While it might be a realistic insight into what couples go through when they're juggling family, jobs, dreams and hopes, it's also pretty funny.

Thankfully there are loads of jokes sprinkled across the two hour and 14 minute film to make the viewing more fun.

But, there was one joke that made Rudd feel a little uneasy.

Universal Pictures

Speaking to Shortlist Magazine, the actor said: "Sometimes, [producer] Judd [Apatow] will yell out lines for me to say during filming and I never filter anything – I just repeat what he says.

"There’s one scene in this movie where he yelled out this comment for me to say about David Schwimmer.

"I thought it was funny, but Schwimmer is a friend of mine – and I didn’t want to say anything that would make him mad.

"So I laughed when I said the line because I thought that would ruin the take and it wouldn’t get used.

"When they asked me to do it again I said no. But then they ended up using that take in the movie."

The joke was about Schwimmer's sexual prowess and Rudd felt so awkward about the moment that he sent the Friends star an email to give him the heads up.

When the article was published nine years ago, Schwimmer hadn't replied.

Hopefully he has by now.

Universal Pictures

This is 40 was loosely based off the couple from Apatow's movie Knocked Up.

Rudd says the comedy legend got the idea to do a sort-of spin-off movie about Pete and Debbie after seeing the success of the 2007 flick.

He explained to Shortlist Magazine: "When he asked me to do it I was kind of surprised.

"I guess the fact that he’d made Forgetting Sarah Marshall and then done a spin-off with Russell Brand’s character for Get Him To The Greek got him thinking that this idea could work."

Who knows what other characters could get the same treatment from Judd Apatow's universe.

Perhaps the hilarious cops from Superbad or maybe Ted from Bridesmaids.