I don't know about smoke detectors, but most public restaurants get checked by the staff pretty often.. also it's a BIT conspicuous to come out of a bathroom that REEKS like kb, with red eyes and a smile on..

I suggest smoking at home, or in a car. Then again, I shouldn't talk. I get high at work, before or after class, in store bathrooms, restaurants, gas stations, etc.. I pretty much smoke where and when I can. so perhaps, ignore my advice. I don't know.