A little more on 2P. It is a reference to a pallette swap in video games. In early video games they would use the same sprite but just change the colors because there wasn't enough room in ram or they may have only been able to display a limited number of colors on screen at the same time.
This also happens in multi player games when two or more people pick the same character.
Must ... resist ... urge ... to ... lick abs. Begone, you fiendish fetish.
Pinky: ... Ah that's the stuff
Brain: Welp, boys were back in business
Penis: ... I never went OUT of business, hmph
Heart: ... Oh no, I'm losing the battle here