It's High-Five Ghost's birthday and Muscle Man doesn't invite Mordecai and Rigby to the party supposedly due to accidentally spilling soda in his face that morning. After several failed attempts to get invited and then subsequently attempting to crash the party, Mordecai and Rigby enlist the help of High-Five Ghost's brother Low-Five Ghost to get in by turning them into ghosts, only to find that they'll be stuck as ghosts forever if they don't scare someone...
Tropes:
- Batman Gambit: Muscle Man's whole prank hinges on the fact that Mordecai and Rigby would want to go to an awesome party that they weren't invited to, and that they would pick Muscle Man to scare or risk staying as ghosts forever.
- Crying Wolf: When Muscle Man starts choking on party food after faking a fatal heart attack, Mordecai initially refuses to help him as he and Rigby believe it's another prank. When Muscle Man nods his head "no" and slumps over, Mordecai and Rigby realize it's not a prank and Mordecai rushes to his aid.
- Disproportionate Retribution: Muscle Man prepared an elaborate prank that involved faking his own death all because Rigby spilled soda in his face that morning.
- Dude, Not Funny!: Nobody other than the people in on the prank thought Muscle Man's death scare prank was funny and the party goers almost left.
- Fright Deathtrap: An accidental "Scared Stiff" example: Mordecai and Rigby scare Muscle Man so bad they give him a heart attack that kills him. Except not really, it was part of the prank.
- Innocuously Important Episode: Marks the point of the series where Mordecai and Muscle Man quit being arch rivals and start to get along.
- Hidden Depths: It's revealed Mordecai knows how to perform the Heimlich Maneuver.
- Is There a Doctor in the House?: When Mordecai and Rigby supposedly give Muscle Man a heart attack, they call for a doctor. HFG and LFG's Dad, pretending to be a doctor as part of the prank, pretends to perform CPR on an apparently not breathing Muscle Man before declaring him deceased. Of course when Muscle Man starts choking, HFG and LFG's Dad admits to not being a real doctor.
- Minor Injury Overreaction: Muscle Man's response when Rigby accidentally spills soda in his eyes twice? Scream like a banshee and push the the table into the wall while flailing, and then pull an elaborate prank where he makes them think they killed him to get back at them.
- My God, What Have I Done?: Mordecai and Rigby are naturally horrified when they believe they accidentally killed Muscle Man. When it's revealed to be a prank, they're less than amused.
- No Sympathy: How does Muscle Man react when Rigby starts choking? By laughing at him.
- Not on the List: Muscle Man hired Bobby as a bouncer to keep Mordecai and Rigby out of the party, though he lets Bobby let a random passerby in just to taunt them.
- Overly Pre-Prepared Gag: Muscle Man's prank.
- Rhetorical Question Blunder: When Benson asks if the party's still on, Muscle Man retorts "Does this answer your question?" tries throwing a tape into the boom box, missing. Benson responds that it did not answer his question.
- Uninvited to the Party: Muscle Man refused to invite Mordecai and Rigby to HVG's birthday party and the two spend the episode trying to get invited, and when that fails, crash it. Played with as it was a reverse psychology trick to get them to come because it was part of a prank to get back at them for spilling soda in his face.
