My boyfriend wants me to "simulate sex"

So, my boyfriend wants me to "simulate sex" with his friend. I'm an acting major, and he has always (what I thought was jokingly) said that he'd love to see me do a sex scene. He showed this artsy kind of "porn for women" kind of video And said it would be art, and I wouldn't be having real sex. I don't like his friend too much, but he is attractive I suppose. I'm a pretty reserved and inexperienced person, so this kind of makes me nervous. But I am an actor, and I kind of think it would prepare me for an actual intimate scene if I ever had to do one. I'm just not sure what to think and would like to talk to people about it who have heard of similar situations or just have any advice on the subject.