In "Dizzy", they meet Pops when he falls to their domain, the Dizzy World, and gives him ice cream, explaining how they outlawed speeches (which is the reason Pops came there), making it illegal. They also made it illegal to not enjoy ice cream. When Pops unintentionally creates a speech while ranting to Mordecai and Rigby (who are trying to rescue him), Iacedrom and Ygbir get enraged and unsuccessfully attempt to kill Pops.
Iacedrom is the opposite version of Mordecai. Iacedrom wears a fancy black top hat. He appears as a realistic form of Mordecai. Both Iacedrom and Mordecai share similar voices and appearances. The only distinctions between them are that Iacedrom forbids speeches, whereas Mordecai often makes speeches in several episodes. Iacedrom can fly while Mordecai can't.
Ygbir is the opposite version of Rigby. Like Iacedrom, Ygbir wears a black top hat. He is the realistic form of Rigby. Ygbir also doesn't allow speeches. Ygbir and Rigby are both similar in voice and appearance. The only distinction between them is Ygbir is polite and confident towards others, whereas Rigby is very impolite and always has the urge to slack off.
- They are the photo-realistic counterparts to Mordecai and Rigby.
- Iacedrom and Ygbir's more realistic appearances are based on earlier character designs for Mordecai and Rigby. In these earlier drafts, closer to real life, Rigby was the size of an average raccoon and Mordecai was smaller, closer to the size of an actual blue jay.
- Even with a realistic appearance, Ygbir still looks short compared to Iacedrom.
- Both their names are based on the main characters' name spelled backward, but only "Iacedrom" is Mordecai spelled backward correctly. Ygbir's name forwards would be Ribgy, not Rigby. This is so to not confuse another character with a similar name.
- Iacedrom and Ygbir are the fifth villains in the show that Mordecai and Rigby haven't destroyed or defeated, but rather escaped from. The others are Moon Monster, the Coffee Bean, the Grease Monster, and the Graffiti Monsters.
- It may be that Iacedrom and Ygbir are really only in Pops' mind, and are therefore personifacations of Pops' fear of speeches. If so, in the series finale "A Regular Epic Final Battle", as a result of Pops' death in order to kill Anti-Pops in order to save the entire universe in the process, although they didn't appear or were mentioned, Iacedrom and Ygbir were consequently erased from existence along the Dizzy Zombies and the Dizzy World itself as the mind of the person who created them was no more.
- They seem to be the leaders or bosses of all of the dizzy zombies.
- They were seen on hieroglyphs at the observatory in "Pops' Favorite Planet".