The `High School Musical` star, who was attending a Rolling Stones gig at the time, tried to stop the trousers from coming down but the waistband appeared to rip as she tried to walk while Butler was still standing on the hem, the Sun reported.
The brunette beauty looked slightly embarrassed as she was left with her green knickers on show while surrounded by fellow concertgoers.
The 24-year-old actress was seen strolling up to the Staples Center arm in arm with her blonde beau, just mere moments before the unfortunate event.
It was the opening night for the bands `50 & Counting` tour, which will also see them play in Hyde Park in July.
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