1.When a man has hair from his chest leading to his penis that exceeds the "Happy Trail" follicle quota.
2.When a happy trail looks wide enought that you can drive a car on it, that is a happy hike.
i was going to go down on this one guy but when he took off his shirt i noticed he had a happy hike instead of a happy trail
A proposition made to a person to give you head.
Stems from the person following your happy trail.
"Hey Babe, you wanna work out - why don't you take a happy hike?"