To make a bluff with the deliberate intention of being exposed as a loose player. Advertising usually means showing down a mediocre hand in order to give the impression that you play overly loose or that you play a generally weak game. The idea is that other players will then give you more action when you make a legitimate hand. Since people are bad at revising first impressions, this potentially beneficial effect can be long-lasting.
Advertising can also mean anything you do at the poker table to manipulate how other players assess you.