Just a heads up for those who've never done it, if you don't have a vent/exhaust or an open window in your bathroom while you smoke then it will smell like weed afterwards. The steam doesn't completely take away the smell. A little bit of body spray, or a really good air freshener extract (blunt power, yankee candle, etc) sprayed once or twice will cover up the smell completely.
Seriously, though, without a vent things can get pretty tricky if your aim is undercover smoking in the shower.