Hitchhiking. Contact Highs

[_caesar_]

In the glossary of PIHKAL, Shulgin gives a brief detail of this term.

"Sometimes an innocent, drug-free person will find himself strangely disturbed or uncomfortable in the presence of an experimental subject who is, unknown to him, experiencing the effects of a psychedelic drug; for instance in the checkout line at the supermarket. The unconscious awareness (or contact high) can produce a feeling of irritation, or even overt hostility, in the inadvertent hitchhiker, and his or her distress is all the worse for having no apparent reason or understandable cause"

SWIMs experienced this on more then one occasion and finds it fascinating. I'd like to here any of your experiences or opinions on this peculiarity.