this piece on bob dylan meeting the beatles for "a larf," has some insightful details and is pretty interesting if you can get past the many paragraphs in which the author talks about himself.

an excerpt that clearly shows ringo as the guinea pig for things lennon wasn't quite comfortable with:

"Bob handed the joint to John, who immediately handed it to Ringo.

'You try it!' John commanded.

That act instantly revealed the Beatles' pecking order. Obviously, Ringo was the low man on the totem pole. When Ringo hesitated, John made some sort of wisecrack about Ringo being his royal taster.

'Inhale with a lot of oxygen,' I instructed. 'Take a deep breath of air together with smoke and hold it in your lungs for as long as you can.'

As Ringo kept taking hits, Victor, Bob and I waited for him to pass the joint to John, who was sitting right next to Ringo. But the Beatles were unacquainted with the rituals of pot smoking. Pot smokers share joints because it's precious stuff. It's illegal, expensive and not easy to get. Pot smokers don't waste any smoke letting the joint burn idly like a cigarette. That's what's known as 'Bogarting' a joint, in honor of the way Humphrey Bogart held a lit cigarette in his fingers until the long ash would fall from its own weight. I neglected to instruct Ringo about passing the joint and it was obvious that he was going to hold onto it as if he were smoking a cigarette filled with tobacco. I didn't want to risk the possibility that Brian and the Beatles might recoil from the idea of passing a joint from lips to lips like a bottle shared by winos on a street corner. I asked Victor to roll more joints. Victor was an expert roller whose joints looked like regular cigarettes."