When it comes to partying, Foreigner out-debauches Aerosmith – says the only musician who would know

Of the seven billion or so people who currently call Earth home, only one has been a member of two of classic rock’s most venerated acts: Foreigner and Aerosmith. As such, multi-instrumentalist Thom Gimbel is in a unique position in terms of knowing what goes on behind the scenes with each act.

And while one would assume the guys in Aerosmith, whose debauchery and self-destructive tendencies are part of rock mythology, would be the heartier partiers, Gimbel, who, along with his Foreigner teammates Saturday visits Parx Casino in Bensalem, Pa. has a surprising spin.

During the years (1989-’95) Gimbel toured with Aerosmith, the band members were, he said during a recent phone call, “very much clean and sober. It was all about fitness and carrot juice and wheat grass. We were even doing blue-green algae – I don't know if that was really healthy. But it was great. It was really a marvelous time; a lot of sushi.”

In 1993, Gimbel briefly joined Foreigner. He recalls walking into his first-ever gig with the group along with guitarist Mick Jones, who today stands as the group’s sole remaining founding member. “He said, ‘Is it true you you never did any real fun stuff [with Aerosmith]?’

“I said, ‘It's very clean and sober.’ He said, ‘Well, as far as fun goes with us, it’s mandatory,’ and he handed me an ice- cold beer.”

Actually, Gimbel admitted, there was at least one time when Aerosmith lead singer Steven Tyler repealed Prohibition.

“It was a very strict rule,” he said. “You were not allowed to do any drinking or any partying around the stage on show days. And if anyone saw you in a bar, you could get sent home.”

But one night in Japan, continued Gimbel, “They were throwing these little bottles up on stage, and we thought it was water. It turned out it was sake. After the show, Steven smelled one and said, ‘This is sake!’ And we’re like, ‘It was nice of those people to give us this much sake.’

“He said, ‘Here, why don't you drink one of these?’ And I was like, ‘No, I could get in trouble.’ He said, ‘How are you going to get in trouble if I'm your boss and I'm the one telling you to drink it?’ I said, ‘Well, good boss!’ (mimicking chugging liquid) Glug! Glug! Glug! Glug! Glug!”

In Foreigner, Gimbel, a 59-year-old Boston native, covers the instruments — including keyboards, saxophone and flute — played by original member Ian McDonald, who is revered in the progressive-rock realm as a charter member of the groundbreaking prog ensemble, King Crimson. He was still in high school when Foreigner’s self-titled debut LP — which boasted such signatures as “Feels Like the First Time” and “Cold As Ice” — was released in 1977 (it went on to sell more than five million copies). But even after almost a quarter-century, Gimbel still revels in his membership in the band.

“It's an absolute honor,” he insisted. “I've always been thrilled and delighted because I feel so fortunate to be able to work with Foreigner.”

Parx Casino, 2999 Street Rd., Bensalem, Pa.; 8 p.m. May 4; sold out.