When you have to masturbate based purely on your imagination, with no porn of any kind. Often used by 12 year olds in dark rooms who have no access to porn, a raging boner, and only the searing memory of seeing up a girl's skirt in school that day.
Scott: I think we should skip the Mexican food for lunch today, it gives me mad gas and we have to go back to work.
Tom: Come chill with me in the fermentation lab this afternoon. We're growing anaerobes today and the stench is so ripe you'd have farte blanche.