The planet Glapflap was first mentioned by Rick in The Wedding Squanchers. He quickly describes how Birdperson fought against Gromflomites at Blood Ridge, on Glapflap's third moon. The light years this planet is said to be away from civilized space is roughly equivalent of the amount of time it would take to humans to understand the incomprehensible Great Old Ones.
Battle of Blood Ridge
The Battle of Blood Ridge was the result of a revolt, from a number of different species, against the Gromflomites. Rick Sanchez is notoriously famed from his sadistic behaviour during the battle, as well as his disregard for protocol set forth in the Blobbadobo Accords. At Ploopsi Point he grabbed an injured Gromflomite and rubbed his testicles on the face of the dying soldier. Nearing the end of the battle, Rick defecated in the mouth of another dying Gromflomite soldier, which would unintentionally serve as sustenance and end up saving the soldier's life, leading to the soldier viewing Rick in a positive light.
Since then 27 glaagnars have passed, and Blood Ridge vets are annually honored with the Remembrance Parade, which now also takes place in the Lil Glapflaps neighborhood (formely San Diego) on Earth