A phrase referencing the fact that future events are unknown and that the outcome of a desired situation cannot be ascertained at the time until said future events unfold.
Jim: I went on a date with Becky last night. I think it went pretty well. I wonder if she's the one?
Greg: Who knows man. Only time will tell.
The act of fucking a girl doggie style, and right when the male is about to climax, he flips her over, sets her pubic hair on fire, and extinguishes it with his jizz.
Dave told that bitch he likes bald pussy, so he had to give her a flaming wally to set her straight