Way before making his marks on St. Elsewhere and NCIS Mark Harmon appeared in a commercial for Kellogg's Product 19 Cereal with his father Tom in the 70's and the commercial featured Mark and Tom being active. I didn't realize that Mark Harmon did commercials and he was pretty good at commercials
Bestie

Hi, Bestie! I did not know Tom was Marks father. That is some good trivia. Thank you, Bestie!
DTK