"Say No to Drugs, Say Yes to Tacos” is a popular Tex-Mex (or Cal-Mex) slogan of unknown origin. First Lady Nancy Reagan began a campaign of “Just say no” to drugs in October 1983. By at least July 1991, a San Diego bumper sticker read: “Say No to Drugs, Say Yes to Tacos.”


funlol
SAY NO TO DRUGS
SAY YES TO TACOS
(Written on a red sign, like a stop sign—ed.)

12 October 1983, Los Angeles (CA) Times, pg. A2:
Nancy Reagan. campaigning to get young people to “Just say no” to drugs, appeared today as co-host of an ABC-TV “Good Morning America” program which was devoted entirely to drug abuse.

17 July 1991, Los Angeles (CA) Times, Metro section, pg. B1:
San Diego bumper sticker: “Say No to Drugs, Say Yes to Tacos.”

27 May 1993, Los Angeles (CA) Times, Metro section, pg. B5:
After months of meetings and planning, nearly 100 catering truck owners and their families met Wednesday in North Hollywood to celebrate the official formation of the Latin-American Catering Truck Assn. (LACTA), which already has an estimated 175 members.

“This is an organization with good goals and we have worked together from the start,” [Mark Kroeker] said. On the podium in front of Kroeker was a sign: “Say yes to tacos, say no to drugs.”

21 December 1994, Los Angeles (CA) Times, Life & Style section, pg. E1:
... beneath a mural of a big, brown-eyed Virgen de Guadalupe, not far from the Tacos Chapalita hut where the motto is: “Say no to drugs, say yes to tacos.”