"2nd hand high" is possible. The lungs can't be efficient enough to capture 100% of the THC you inhale, especially as you age.

It was me and three buddies on a "roadie" (drive and toke). One of my buddies quit smoking, but he didn't mind being around it. After we arrived at our destination(frisbee golf course), he noticeably was acting goofy. He admitted to feeling a little high.


As for a total mental contact high(w/o inhaling any 2nd hand smoke), you would be surprised what the brain is capable of doing with its naturally-occuring chemicals. Something, as in being around someone high, can "trigger" your brain to start producing neurotransmitters that can mock being high. This is a little more extreme, but what do you think flash backs are.