Two Guys in an Elevator was a special video on Nova's channel featuring Sp00n, in which they played a map off of Garry's Mod named "Elevator: Source". The duo rode an elevator that stopped on some rather strange and unexpected floors before reaching the top of the tower.
The whole video revolved around the two screwing around in the elevator, and occasionally stopping on a floor that made little to no sense to them. During their playthrough, however, they experienced an issue with the map. On a certain floor, everyone that normally fills the elevator every couple of floors all boarded at once, and the elevator would be stuck until the map restarted. They never truly finished the map or reached the top floor.