Someone that has gotten some pussy, and is barely leaning over the fence, but can't decide if they like it so they lean backwards over the fence onto a dick, and are in the teetering position on top of the fence about being gay or straight.

When someone runs into a fence with a car

or

when someone runs into your fence with a car.

When your mum fixed fences and you’re as skinny as the stick under a tree

Someone who consistently oversteps their bounds in an offensive manner. Such as taking the last beer when they didn't even buy it, using your car without asking, borrowing things without leaving any form of notification, pursuing ulterior motives with your significant other, secretly stealing your cigarettes or dip while you sleep or blatantly to your face, and similar actions.

The look a person gives you when they don't know which side or thing to choose like being on the fence.

When one is outside and hangs on a fence whilst squatting for a shit

A bisexual person. A fence-hanger is a term that refers to a person who hangs on the proverbial fence - he or she is unable to pick a side on which to committ his or her sexuality, but rather stays near the fence (the middle).