Tickets for the New Orleans Opera Association's 28th annual Mad Hatter's Luncheon at the Hilton New Orleans Riverside (2 Poydras St., 561-0500; www.hilton.com) are on sale. The event starts at 11 a.m. Tuesday, March 27. Patron tickets cost $85, and general admission is $75. There will be a fashion show featuring Saks Fifth Avenue's St. John collection, a celebrity hat contest and auction, a raffle and a silent auction. Proceeds benefit the New Orleans Opera Association. Call Cindi Mistrot at 416-8890 to buy tickets.