The 100th is the fourth episode of Season 5. It aired on October 23, 2013. It's also the 100th episode overall.
The citizens of Orson, Indiana celebrate the Orsontennial - the town's 100th anniversary. During this momentous event, Frankie and Mike find themselves begrudgingly trying to drive a giant cow float in the parade; Axl, Sean and Darrin resurrect Boss Co. and attempt to make some big bucks by setting up a VIP area to view the festivities; Sue, still crushing on Darrin, tries to make him jealous by pretending to be dating Brad again; and Brick tries to earn himself a place in Orson history by entering a contest to come up with the town's new motto, which will be used for the next 100 years.
Ari Welkom, the actor who played the John Cougar Mellencamp impersonator is the lead singer of the neo-psychedelic band Cosmic Suckerpunch.