PRETTY RICKY may be the freakiest boy band ever. The Miami quartet of brothers issued a clean and dirty version of its R&B debut, Bluestars; scored a No. 1 hit with the equally libidinous Late Night Special; and likes to hump the stage while performing in front of squealing, adoring fans. Parents may be horrified, but the adolescent girls understand. The group plays Center Stage Atlanta on Mon., MARCH 26. $31.50. 8 p.m. 1374 W. Peachtree St. 404-885-1365. www.centerstage-atlanta.com.