In Life of Heroes RP 2: Death From Above: Part 2, GIR makes several references to the show Invader ZIM. First, after Q-Pid yells "Yay epic fail!", GIR yells "YAY! I'M GONNA BE SICK!", directly quoting a line from the episode Door To Door. Also, after CM agrees to help GIR and Zim recover the Voot Cruiser, GIR asks "Where's my walnuts?", also a direct quote. (from the episode Room With A Moose) And, later, when he falls asleep on Q-Pid's head, he references the episode Battle of The Planets.
Additionally, after Crash Man, Sia, Zim, and GIR rescue Daria, GIR beatboxes the Invader ZIM theme music.