Word Origin & History
1968, "inhalation of a marijuana cigarette or pipe smoke," U.S. slang, from earlier verb meaning "to smoke a marijuana cigarette" (1952), perhaps from Sp. tocar in sense of "touch, tap, hit" or "get a shave or part." In 19c. the same word in British slang meant "small piece of poor-quality bread," but
this probably is not related.