To freeload is to take food, drink, a bed, wifi, or other good things from people, and give nothing back. It is not a kind word. If someone says you are freeloading, they are fed up: they feel you are using them. Friends may joke with it — “stop freeloading on my snacks” — but the joke still has a little sting. It is informal, and it sounds more American than old British English, though plenty of people understand it now. You freeload on a person, or on their food, sofa, or connection. Though actually, it is not the same as being invited and then returning the favour later. The disapproval is the point: the giving is all one way, and the speaker wants you to hear that. The verb is the younger word; people had freeloader first and then cut it back to make a verb.

白吃白住、佔便宜