A mechanic noticed his co-worker drinking brake fluid at lunch.
"What are you doing, man? You can't drink that stuff!"
"Relax," replied his co-worker, "this stuff tastes pretty good, and I don't drink it all the time."
"Seriously," the mechanic exclaimed, "that brake fluid is poison!"
"Hey, man" yelled the co-worker, "back off! I can stop any time I want."