The next time you bump into a roadie at a local show, be nice — that might just be one of the world's biggest rock stars in disguise.

Admittedly, the odds are fairly low. But as Phil Collen revealed in his recently published memoir, Adrenalized: Life, Def Leppard and Beyond, he and his bandmates in Def Leppard received a secret helping hand from Robert Plant during a stop on their tour behind 1987's Hysteria.

As Collen's book points out, the band was using a fairly unorthodox stage setup for the tour, which required some extra planning to get the group onstage after Queensrÿche finished their opening set. Because of the way things were laid out, they had to lay in wait under the stage in order to make the kind of dramatic entrance they wanted — but they couldn't get under it without attracting the attention of fans.

The solution they devised involved climbing into gear bins and having roadies wheel them into position under the pretense of moving equipment, and when Plant paid them a visit — during a Chicago stop on the 236-date tour — he wanted to get in on the fun.

"Everybody in Def Leppard is a huge Led Zeppelin fan. I kept thinking back to when I saw Zeppelin as a kid back in the mid-1970s, and couldn’t believe Robert Plant actually wanted to come to our show. But it got better," Collen wrote. "When he heard about the way we got wheeled out there every night, he got all excited and asked if he could be part of the clandestine operation that took place before the show."

That's just one example of the horsing around that went on behind the scenes during a tour that captured the band at its peak commercial power, and it offers amusing proof of how much fun Def Leppard were still having even as Hysteria took over the world. "It’s amazing how primitive the whole 'getting to the stage' thing was. But that is theater for you," muses Collen. "Smoke and mirrors has always been a major part of its entertainment."

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