Sorry, but I have to ask.

[Newguy86]

I'm a random smoker. Maybe twice a month. I was wondering how long I have to go without smoking to pass a urine drug screen. I'm a fat guy if that helps.

[killerweed420]

You'd better pickup some cheap thc strips off ebay and check yourself to see how your body deals with it.
I use to smoke on sunday,monday and tuesday nights and was clean by saturday. But everyone is different, so test yourself and see how you do.
Or just go the simpler route and sub.