The ad in USC's Daily Trojan newspaper promised that a new "Star Wars" trailer would be shown at the school's Bovard Auditorium.
"Of course, the joke was that we never said exactly what kind of trailer," pointed out senior Michael Carter of the Skull and Dagger Society, which placed the ad.
An estimated 300 excited students, and some members of the media, lined up outside nevertheless. Suddenly they had to make room for a car pulling a U-Haul trailer with a poster that said: "Star Wars Trailer--Episode 1."
No movie trailer was shown.
Many disappointed attendees had skipped classes for the sneak preview.
"A friend of mine in Boston called me at 8:30 a.m. and said that he found on the Web that ['Star Wars' creator] George Lucas was coming," one student complained to the Daily Trojan.
The prank continued a tradition of Skull and Dagger, USC's secret honorary society. Each year, the group's new members must stage a stunt as part of their initiation.