B-AD BOYS: Workers at ad agencies across the nation are taking a break from hawking toothpaste, burgers and cars, and on Monday will try to sell themselves at Ad Band II. At this annual battle of the bands concert, expect some pretty good rock as well as a couple of train wrecks. It’s the kind of concert that has the potential to be a load of fun, and besides, proceeds from the show will be used to benefit the music programs at New York City schools. As for the bands, they’re competing for a tin cup and bragging rights. Tickets are $25. Showtime is 8 p.m. Irving Plaza, 17 Irving Place, near 15th Street; (212) 777-6800.