Here’s how they pulled off Mac’s insane dance scene in the Always Sunny finale

It’s Always Sunny In Philadelphia’s Rob McElhenney has gone to some pretty extreme lengths for the sake of a joke. Back in season 7, he gained nearly 60 pounds because he thought it would be funny if his character looked worse as the seasons wore on. McElhenney has since pushed himself to the other end of the spectrum and, these days, Mac is looking comically jacked. In this week’s season finale, it was revealed that the reason Mac is in such good shape is that he’s been preparing an elaborate modern dance piece in order to express his emotional turmoil to his imprisoned father. Recently, Vulture got the inside story on this breathtaking surprise performance, which apparently took months of work and planning to make happen.

First, in order to get into the shape necessary to pull this off, McElhenney worked with celebrity trainer Arin Babaian, who gained notoriety working with Channing Tatum on Magic Mike. Once he was in good enough shape to dance for two hours a day, he reached out to choreographers Alison Faulk and Leo Moctezuma, and together they crafted the emotional modern routine that McElhenney would ultimately perform alongside professional ballerina Kylie Shea. Through all of this, McElhenney insisted he had “zero ability to dance” and was “not a very limber person.” The choreographers—and ultimately the viewers—would disagree.