This is not a very good commercial even by 1985 standards, but I have a good reason for choosing it; it's politically incorrect as hell by 2009 standards.

9.  Stanley Studfinder commercial

This one is amusing for two reasons:  First, the ad agency obvioulsy thought it was the first one to think of the tired old "stud finder" joke.  (If any male over the age of 12 picks up a stud finder, he is required by law to use it on himself to the non-amusement of anyone who happens to be standing nearby.)  Second, Kasey Kahne is the one with a reputation as a ladies man.

8.  Dale Jarrett UPS commercial 2001

7.  NASCAR Ride-Along Program

6.  Sprint Cup wild animals commercial

5.  NAPA Michael Waltrip fan letters #1

One thing I love about Michael Waltrip is his self-deprecating sense of humor.  I like it enough that he has two commercials in this countdown.

4.  NAPA Michael Waltrip fan letters #2

3.  NASCAR Fan Controller (Toyota) 2008

2.  Dale Earnhardt Sr. and Dale Earnhardt Jr. Chevy commercial

1.  Adventures of Rusty - The Woodchuck

If this commercial doesn't cause you to convulse with laughter, then something inside of you is broken beyond repair. 

HONORABLE MENTIONS:

Related links:
Funny NASCAR auctions
Bad NASCAR tattoos
NASCAR paint-scheme FAIL
NASCAR merchandising FAIL