I remember John Moschitta, Jr.'s 1981 appearance on That's Incredible! like it was yesterday. (That's Incredible! had a profound influence on me, that I think is reflected in my blogging.) The next day at school, my friends and I all tried to talk really fast. I bet that just delighted our teachers. After this episode, Moschitta, Jr. was hired by ad agency Ally & Gargano to star in the "Fast Paced World" Federal Express TV commercial that's repeatedly ranked in the industry as one of the top ad campaigns ever.
UPDATE: In the comments, Christopher575 reminds me that Moschitta, Jr. also did a terrific Micro Machines commercial in the 1980s.