In 1975, I had a tangerine flake K2, really clean with a chrome Kerker pipe. (Same bike I now have but it's been way changed up by now).
I was taking a class at ASU and parked it in the lot. When I came out there was a 1/4 square sliver of a notebook page, torn out, with the words "Nice Bike!" on it, tucked under the seat strap.
Still have that paper.