“Don’t drink and drive—you might hit a bump and spill your drink”

“Don’t drink and drive—you might hit a bump and spill your drink” is a jocular saying that has been printed on gift items, such as T-shirts, bumper stickers and posters. The saying disregards the fact that states have open container laws that make this action illegal (and not just a poor choice of where to drink).
 
The saying has been cited in print since at least 1987 and is of unknown authorship.
 
 
3 March 1987, Philadelphia (PA) Inquirer, “The scene, in Philadelphia and its suburbs,” pg. B2:
Above the bar was a sign that said, “Don’t drink and drive. You might hit a bump and spill your drink.”
     
Google Books
The Washingtonian
Volume 22
1987
Pg. 173:
Outside on The Corner, an International Harvester road wagon filled with a dozen sorority girls whips around the block. On the back is a sticker that says, “Don’t Drink and Drive—You Might Hit a Bump and Spill Your Drink.“
 
2 June 1988, Dallas (TX) Morning News, “What’s everyone laughing about? Dallas has become a serious hub of comedy” by Ken Perkins:
“Don’t drink and drive,’ McGuire says before leaving the stage. “You might spill your drink.’
(Gene McGuire at the Addison Improv—ed.)
 
6 October 1988, Los Angeles (CA) Times, “Drinker Tells Key to Survival: Drive ‘Like a Saint,’ Not a Sot” by Jan Hoffman, Orange County Life, pg. 5:
“I love that bumper sticker that says, `Don’t drink and drive, you might hit a bump and spill your drink.’”
 
Google Books
Words of Wisdom
Compiled and edited by William Safire and Leonard Safir
New York, NY: Simon & Schuster
1989
Pg. 384:
Don’t drink and drive. You may hit a bump and spill your drink.
 
Google Books
A Guy Walks Into a Bar…:
501 Bar Jokes, Stories, Anecdotes, Quips, Quotes, Riddles and Wisecracks
By Michael Lewis
New York, NY: Black Dog & Leventhal Publishers, Inc.
2005
Pg. 25:
SIGN SEEN IN BAR:
Don’t drink and drive.
You might hit a bump and spill your drink.