The act of shadily leveraging an oppurtunistic situation for some sort of personal again, at the expense of a faceless corporation or complete stranger. Scams are rarely illegal, but require a good eye for the oppurtunity, clever manipulation of the situation, loose morals, and confidence in your ability to fabricate lies. Scams can be as simple as getting drive-thru then stopping back 10 minutes later to say they forget one of the burgers, or as complex as...well, the sky's the limit. Despite the shadiness of a scam, the person perpetutating the scam, the "scam-artist", is usually a very intelligent, well integrated member of society who merely never passes up an oppurtunity.
Guy1: Dude, lets scam our way into the movies tonight, because there is no way I'm paying $10 for some cliche, poorly written Hollywood crap-fest.
Guy2: Alright, I'm in.