"If you can eat it, you can beat it" - Weeds

I would just suggest going into the bathroom for a monstrous dump in the middle of the night, turn on the fan and smoke. When you are done smoking, just sit there for a few minutes letting the smoke dissapate before leaving. Before you do go, make sure to flush the toilet and spray some anti-shit-fresh-clean-smell-spray into the air covering up that good ol' ganja smell.