My sister has pulled some classics over the years. When she was in high school she super-glued the school librarian's telephone and receiver together. It was one of those big, old-fashioned phones. Phone rang, and the poor librarian nearly knocked herself out.

Once sis somehow rigged a co-worker's computer so that when the co-worker tried to sign onto the Internet, her phone rang instead. The co-worker kept answering the phone, finding no one there, and couldn't figure out why she couldn't get online.