Arbolian Mentirososians are an alien race originating from the planet Arboles Mentirosos, though can be found on many other planets in the galaxy.
One Arbolian Mentirososian witnessed Rick Sanchez take Roy off the grid in Roy: A Life Well Lived while on a visit to Blips and Chitz. The same guy later appeared in the same Blips and Chitz commercial as Rick.
The Arbolian Mentirososians' homeworld, Arboles Mentirosos, got abducted to unwillingly take part in the intergalactic Cromulon TV reality show Planet Music. They competed in season 988 against Earth, Parblesnops, the Scrotians' planet and the Larva Aliens' planet. They were the second to perform, but ultimately lost to Earth's song "Head Bent Over". Their home planet was thus destroyed, but the race lived on with the Arbolian Mentirososians settled on other planets in the Galactic Federation.
An Arbolian Mentirososian came to Birdperson and Tammy's wedding on Planet Squanch. During the reception, he took part in the gunfight with the Gromflomites, using four guns at the same time. Unfortunately, he was shot and killed like many other guests.
- Strangely, despite their planet being destroyed by the Cromulons, a few of them can be seen during the wedding crash in "The Wedding Squanchers", along with other recurring background alien species. This suggests some members of the species were off-world when their planet was destroyed, and thus survived the destruction.