You know the guy. He's always a quarter short for bus fare, didn't bring a lunch. The book store was out of copies of the book he needed for the course; can he borrow yours? He lost his umbrella, or his lawnmower is broken, or the carryout was closed, so he'll drink yours. Surely you don't mind, old buddy?
I do mind. Mooching is a behavior that should be left behind when one leaves home, and the moocher is taking advantage of our natural instinct to help others. Are you inflicted with a moocher? Here are some suggestions for your consideration.
Is the moocher really your friend? Often, the answer is no. You're merely a soft touch. Facing up to this fact can help you build up the moxie to tell the mooch to put the touch on someone else, thank you very much. In doubt? Try mooching something from the mooch. Moochers never willingly allow others to mooch off of them.
Be prepared for drama. Mooches love to play the part of the aggrieved, as though refusing them the right to mooch is denying them an inalienable right. Recruit a real friend to witness the mooch's protest with you, to help you keep perpective.