Inspired by Paul Thomas Anderson's The Master (2012).
The personality machine that the three use on the couch is the same photon level machine that is used in "It's Always Sunny in Philadelphia" (2005) {Mac and Dennis Buy a Timeshare (#9.4)}. There is a callback to the joke as to where they put their feet while they use it.
One of the ass-kickers is called "Tiny" and the character works in construction. This is a nod to Greg Hamlin, the show's construction coordinator, whose nickname is "Tiny".
The "Bend and Snap" workout routine created by Mac is clearly inspired by the cult choreography scene in "Legally Blonde" performed by Reese Whiterspoon and Jennifer Coolidge. Frank almost replicates the scene later. This is just another proof of the Gay Mac theory.