Sometimes in the middle of the night one has to get up and go pee. Well you have the mask on and its too much trouble to have to take it off and then have to put it back on again so you just leave the mask on and disconnect the hose from the machine, right? Okay, so on the way to the toilet you throw the hose over your shoulder and let it dangle behind you so it will not get soaked, if you know what I mean. So the hose is dangling down your back and you are peacefully taking part in a natural function, then you release some gas, not realizing the end of the hose rests at the area of release. You breathe in as you normally would and quickly find out that you have straight lined a fart through the hose and into your nose. A real eye opener.