It may have started off as a joke — models prancing down the catwalk in their underwear — but Victoria’s Secret Fashion Show has transcended its status as a voyeuristic spectacle for young men to become a pop culture phenomenon and a formidable franchise for CBS. Last night’s special drew an eye-popping 4.9 rating/12 share in adults 18-49 and a 5.2/14 in 18-34 at 10 PM, the highest ever for the franchise in both categories.