When you fart in your sleep, and smell it in your dream.
I was having the best dream, satisfying three beautiful ladies at the same time(feeding them Ben & Jerry's in bed, what else?), and suddenly smelled a bad fart and instantly realized I had farted in real life in my sleep and was smelling it in my dream. ....since this explained the ladies not minding at all, or noticing, I simply made note of the lucid flatulence, put down the ice cream, and had my way with the three of them.
E. Benson Feb 4th 2021