Starting October 9, purchase a PS4-branded Taco Bell Big Box and text the included code for a chance to win a bundle including a white PS4 and Destiny. Taco Bell and Sony Computer Entertainment America promise to pick a winner every 15 minutes during the promotion, which ends on November 19.
The bundles include a white PS4, white DualShock 4, a physical copy of Destiny, two additional Destiny download codes, a voucher for the Destiny Engram "Gear Pack" and a 30-day PlayStation Plus membership (available only for new Plus members only). Plus, you get whatever food you ordered in the first place.
Taco Bell has held these promotions before, notably with the Vita and the launch of the PS4. See links for the official rules and a visual breakdown of the contesthere.