The 35-year-old actor had a good laugh when he joined Conan O'Brien and Andy Richter on Thursday's Conan, and was asked if he got any "sexy notes" while playing the lead role of Christian Grey in the erotic books-turned-movies.
Dornan admitted that it was actually Johnson -- who portrays his love interest, Anastasia Steele, in the Fifty Shades films -- that is "quicker" to offer up suggestions.
"I guess there's a sexy way to take off a girl's underwear," he explained, while demonstrating what not to do.
"This is when you're pranking someone," O'Brien quipped, doing the motion himself.
"There is a more delicate, sensual way to do it," Dornan instructed. "It's thumbs to the side [of the underwear], and then you sort of shimmy it down."
In addition to teaching her co-star a few things, Johnson told ET's Cameron Mathison it takes "serious psychological preparation" on her part to get into the right mindspace for a Fifty Shades sex scene.
"I really had to get ready for it each time and know exactly what we were going to do and how we were going to accomplish shooting the scenes, the more intimate ones," she explained. "Over the course of the three films, it never got easier. It wasn't like, 'Oh, this old thing,' you know?"