Hugh Jackman started the bit by explaining that only one song coaxes Michael Fassbender away from his trailer.
"He'll wait in there for hours and hours -- he's very difficult, very ornery on set," Jackman joked. "So there was really only one song [that would make him], and I used to get the sound guy to play it very loud in the studio as he came in, just so he could get his mojo up."
Norton asked Fassbender to walk off stage so he could re-enter to Robin Thicke's "Blurred Lines."
Watch the magic happen below:
X-Men: Days of Future Past hits theaters May 23.