^ the instance that springs to mind for me was turning up to a rehearsal studio to practice with my band, having just eaten about 50 grams of fresh p.cubensis.
I didnt act out of character; I usually rock up to rehearsal stoned or go out for a joint halfway through or whatever.
My bandmates at that time did not use psychedelics with any regularity (if at all). The signs to them would not have been obvious - I was playing it cool, set up my equipment and started playing.
I didnt say much - nothing to give myself away, or to create an atmosphere of 'psillyness' or trippy behaviour.
I've played in bands for years - I just set up and did what I always do.
No silly grins or confused fumbling - i behaved as deliberately coherent as I could manage; and as an experienced tripper, and long-time working musician, this was no problem. I'd just caught a cab there, and the process of making small talk to the cabbie and negotiating paying the fare had loosened me up somewhat in regards to "acting straight"
Throughout the rehearsal, every member of the band (except me) displayed classic signs of psychedelic behaviour.
The bass player commented "I can't stop laughing" when nothing was particularly funny, the drummer was clowning around and mentioned that he couldn't feel his hands, while the singer spent an inordinate time making strange noises through the PA and getting tangled in the mic cable.
I was the most "sober" person in the room, yet I was tripling pretty fucking hard.
It was a really strange sensation, and not one I put down to suggestion (none of these people had taken mushrooms, or knew that I had dosed before rehearsal) or my own warped perception.
The rehearsal room scenario was very familiar - a weekly occurance - and the way my friends behaved was extremely out of character, very reminiscent of a bunch of trippers - and I just sat back and watched.
It was quite surreal, and not the only time I've experienced so-called 'contact highs' - just an example that stands out to me.
I can think of instances where sober people have been swept up in the excitable hysteria of tripping friends, but this was no such occasion. It was a fucking trip, but not in a way I couldn't "get my head around" or that caused confusion.
It was just extremely interesting - and remains so to this day.
The "magic" of psychedelics? You bet! Until scientific studies into such occurrences are able to be undertaken in objective scenarios, I'm happy to ponder on the great mystery of this one.
Placebo is a powerful thing - but lacking any form of suggestion that a substance has been taken, I don't see how it can account for contact highs. There is beauty in such mysteries, to me anyway.