Tommy Lee launched a fan scavenger hunt to raise awareness of an animal charity's SeaWorld Kills campaign.
The Motley Crue drummer hid a SeaWorld Kills t-shirt at the band's gig in San Diego, with the fan who found it enjoying backstage access to meet the group.
A vocal animal rights activist, Lee supports the campaign led by PETA (People For The Ethical Treatment of Animals). He has posted strongly-worded tweets highlighting the treatment of orca killer whales at SeaWorld centres.
PETA Senior Vice President Dan Mathews says: "In addition to the buzz generated at the show, Tommy's half-million Twitter followers all learned about the cruel treatment and confinement of orcas at SeaWorld, which is a huge boost to our campaign."
Lee and PETA will conduct similar scavenger hunts at Crue shows in Texas and Florida, which, like San Diego, are home to SeaWorld centres.
SeaWorld's reputation has been damaged in the wake of the documentary Blackfish which raised questions about the marine park's treatment of sea life and its staff.