Mordecai and Rigby must save Benson from an evil party company.
s04e01 - Exit 9B Part 1
s04e02 - Exit 9B Part 2
s04e03 - Starter Pack
s04e04 - Regular Show Presents Terror Tales of the Park II
s04e05 - Pie Contest
s04e06 - 150-Piece Kit
s04e07 - Bald Spot
s04e08 - Guy's Night
s04e09 - One Pull Up
s04e10 - The Christmas Special, Part 1
s04e11 - The Christmas Special, Part 2
s04e12 - Firework Run
s04e13 - The Longest Weekend
s04e14 - Sandwich of Death
s04e15 - Ace Balthazar Lives
s04e16 - Do or Diaper
s04e17 - Quips
s04e18 - Caveman
s04e19 - That's My Television
s04e20 - A Bunch of Full Grown Geese
s04e21 - Fool Me Twice
s04e22 - Limousine Lunchtime
s04e23 - Picking Up Margaret
s04e24 - K.I.L.I.T. Radio
s04e25 - Carter and Briggs
s04e26 - Skips' Stress
s04e27 - Cool Cubed
s04e28 - Trailer Trashed
s04e29 - Meteor Moves
s04e30 - Family BBQ
s04e31 - The Last LaserDisc Player
s04e32 - Country Club
s04e33 - Blind Trust
s04e34 - World's Best Boss
s04e35 - Last Meal
s04e36 - Sleep Fighter
s04e37 - Party Re-Pete
s04e38 - Steak Me Amadeus
Two groundskeepers, Mordecai (a six-foot-tall blue jay) and Rigby (a hyperactive raccoon) are best friends who spend their days trying to entertain themselves by any means necessary, much to the displeasure of Benson (their boss, who is a gumball machine) and to the delight of Pops (an older, lollipop-headed gentleman).
Their everyday pursuits often lead to things spiraling out of control and into the surreal: they open portals to other dimensions, summon demons via an -80s arcade game and accidentally use choreographed dance moves to send co-workers to the moon.