In college, there was a rumor that I was dating the drummer of the campus christian group I attended. We were never more than friends, and we both laughed about it.
In elementary school, someone's mom started a rumor that I was on drugs, because my older brother was a bit of a delinquent. That one sucked. I was often asked why my eyes were bloodshot (allergies, and contact lenses) and questioned about my "suspicious behavior." I was a quiet kid, mostly - apparently that meant I was on drugs.
Location: Napa, CA