"4" is the name of the club in the movie where The Clash at Demonhead's after-party was held. It is where Scott's battle with Roxy took place. The number four is a reference to the fact that Roxy is the fourth evil ex. This is done with the other exes as well like when Lucas Lee's trailer was labeled 2, Todd Ingram had a 3 on his shirt and Gideon Graves had his stats on his pixel katana (all 7) and the fight was put on screen as Level 7.
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