Hidden Camera Prank With Cory Monteith Doesn't Go as Planned on 'Ellen' (VIDEO)

Cory Monteith of 'Glee' plays a hidden camera prank on an unsuspecting yoga instructor, but things don't go quite as planned when the instructor leaves on 'The Ellen DeGeneres Show' (weekdays, syndicated).

Via a hidden microphone, Ellen DeGeneres has Monteith loudly declare his massive celebrity ("I'm a big star!"), ask not to be touched during the session, toss around a ball of invisible energy ("Catch it! Catch it! Catch it! Catch my energy!"), and babble gibberish.

But, the instructor isn't having it, and walks out with the excuse of being late for another appointment. "Oof!" Monteith later said. "She really needed to leave."

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