I was reading this thread and had a very vivid flashback.
Back in my stoner days, I used to smoke weed in my room, through a bong and then hold the smoke in for a bit and blow it carefully out the window. I was always very careful and this lasted for years...anyway the day arrived, no one was home so I was confident in packing an extra large special... the chuff on the cone burnt as it was large and took a while to inhale in and it let off a smell inside my room...usually when no one is home, I move around the house without paranoia...I went into the toilet, bang my mum and little brother come home earlier than anticipated...
Them: What is that smell?
Me: I was smoking a cigar in the toilet...(sort of rushed, still wasn't feeling effects yet)
They bought it, and called me an idiot.
A long while later, my brother smelt that same smell in the locker rooms at his school. He finds out exactly what that smell is and tells me. He has never told my parents though, and we laugh about it.
With regards to weed, that was the closest to be busted. I miss weed...