Scotch Tape

I found this fun fact on 3M's website:

Richard Drew invented the first masking tape designed to help auto painters to make two-tone paint applications, a Roaring '20s craze, neat and easy. Drew was eager to have the tape sampled by its intended customers. He brought a prototype roll to a St. Paul auto painter. The painter carefully applied the masking tape along the edge of the color already painted and was just about to spray on the second color when the tape fell off. The annoyed painter examined the 2-inch wide tape and saw that it had adhesive only along its outer edges, but not in the middle.
Annoyed, the painter said to Drew, "Take this tape back to those Scotch bosses of yours and tell them to put more adhesive on it!"

The name – like the improved tape it inspired – stuck.
Scotch is a trademark of 3M.