Before she was rubbing elbows with the President Saturday, LindsayLohan was giving the crew of Glee hell.

Sources tell E! Online that the starlet showed up "three hours late" and was a "total nightmare" for her guest spot on the show. One insider says, "When she did finally arrive, she just didn't want to be there. She did not want to work. She had not memorized her lines, and she kept disappearing so no one could find her."

The source adds, "One of her demands has to do with her trailer size. The cast is already worked to death and then she puts everything behind. She is a diva!"

Her spokesperson called the rumors "utter B.S."

In the episode, slated to air May 15th, Lindsay plays herself as a judge at the "Nationals" competition.