Seems pretty obvious, depends on the context I guess. They are making it known what belongs to them.
Someone is lifting up one leg and ******* on trees, cars, and whatever he wants others to keep away from.. :D
A surveyor is marking your property boundary
Setting their boundaries.
Saying back off, it's mine.
People do this with other people.
It means that they are staking their claim in something or someone, warning others to back the hell off.
Claiming ownership of something I presume