Taco King is a costumed mascot for the as named fast food chain that beats up Roger in "All About Steve" for occupying his corner when he tries to escape from the confines of the house by wearing a competing costume for Jumbo Juice to hand out fliers.
When Roger gets irritated because Francine brought him a taco from Taco Barn instead of Taco King while they fake his kidnapping in "Frannie 911", he throws it at her and has a temper tantrum.
Roger's cover story for getting a sample of xenoplasm in "Office Spaceman" involves spotting an alien at a Taco King salsa bar.
Snot mentions taking Roger's persona of Jenny to Taco King on a date in "Jenny Fromdabloc".
When guest Rhonda Hughart Appears on Morning Mimosa to tell the hosts about her diet, she is pressure to describe the number of mimosas that could be drank while on the diet. Caught unaware, she nervously answers with only one, causing the audience to pelt her with tacos from Taco King in front of a "Wall of Shame."
Klaus has to rush Hayley and Jeff out of the bathroom in "Roger's Baby" after eating at Taco King.
A Taco King is located next door to the Richard and the Twins Strip Club in "Cheek to Cheek: A Stripper’s Story".
Francine explains that she prefers to have her bowel movements at the Langley Falls Library due to an incident with Taco King Barbacoa tacos causing diarrhea on a flight to Maui in "Flush After Reading".