The singer/actress has signed up as a guest host for the new season of the popular series, previously fronted by Ashton Kutcher, along with stars including Justin Bieber and Kellan Lutz.
However, Cyrus kept one of the pranks close to home by turning on her actor boyfriend Hemsworth.
The former Hannah Montana actress tricked The Hunger Games star during a night out, telling him she had seen two naked people climb into her SUV car.
She says, "Oh my God babe, there are two naked people in my car right now!" and Hemsworth rushes over, banging on the windows and yelling, "Get out of the f**king car right now!"
A cop then approaches and the Australian actor, who is visibly furious, starts ranting, "You're doing nothing!" as he attempts to sort out the situation.
The episode airs on America's MTV channel on 29 March (12).