i smoke in the bathroom every day... ive had some fucking close calls too. the best way to do it is make a lightbulb vape and use that to smoke. blow the hits into a dryer-sheet tube, in the direction of the fan. i dont have a window in my bathroom so thats not an option. also turn the shower on as hot as it can go, the steam masks a bit of the smell. spray some deodorant and youre set.

i usually get lazy though and just turn the fan on and smoke out of my pipe, the bathroom smells like weed for 30 mins after im done. almost got me caught about 3 times so far.