The Harp Inn, 130 17th St., Costa Mesa. (714) 646-8855. A bar without pretense for people who'd rather get poked in the eye than take a drink in some place like Irvine. They have OK Irish music here on the weekends; occasionally an exuberant patron takes the stage about closing time to work out on a Celtic folk song or two. Plus which, they put out a happy hour spread of Ritz crackers and tuna fish.