Ah, I learned it from Les Stroud aka Survivorman, who is the real deal, seems like Bear got it right for once.

(Should be noted it’s not a good method and still has hazards, but could save your life if you don’t have another option- similar to how how Les will advocate for simply drinking from a mountain stream if you can’t purify- more than likely you won’t get giardia- even if you do, better than dying of dehydration after 3 days of no water)

This is actually a survival technique if you have water than may not be quite potable to drink, you can essentially drink through your ass and not get sick