The Gabbo Show is a show that only appears in the episode Krusty Gets Kancelled. This show competed against The Krusty the Clown Show, airing in the same 4:00 PM slot as Krusty's show. Gabbo is the titular puppet that presents the show alongside Arthur Crandall.
Gabbo's show copies some of the elements from Krusty's show, such as his crank call routine (which was stolen from Steve Allen), and also aired The Itchy & Scratchy Show at one point.
Krusty attempted to compete against the Gabbo Show through various means, but they failed as Gabbo's show became even more popular than Krusty's, the last straw being the airing of The Worker & Parasite Show, which got Krusty's show cancelled.
Despite Bart's attempt to sabotage the show by filming Gabbo saying "All the kids in Springfield are SOBs", his show remained on the air as Kent Brockman got in trouble for making a similar remark.
The last mentioning of the show was when Krusty got a bunch of stars for his comeback special, and Gabbo and Crandall only had Ray-Jay Johnson as a special guest, which caused Gabbo's show to fall off the public's eye while Krusty's special became a big success.