NEW YORK — Unilever’s Omo detergent is adding an unusual ingredient to its two-pound detergent box in Brazil: a GPS device that allows its promotions agency Bullet to track shoppers and follow them to their front doors.

Starting next week, consumers who buy one of the GPS-implanted detergent boxes will be surprised at home, given a pocket video camera as a prize and invited to bring their families to enjoy a day of Unilever-sponsored outdoor fun. The promotion, called Try Something New With Omo, is in keeping with the brand’s international ‘Dirt is Good’ positioning that encourages parents to let their kids have a good time even if they get dirty.

Omo accounts for half of Brazil’s detergent sales and is already found in 80% of homes there, so Unilever’s goal is more to draw attention to a new stain-fighting version of Omo and get it talked about rather than looking for a big increase in sales.

That made the idea of doing a promotion where the prize finds the consumer, rather than the consumer having to look for the prize — and maybe not bothering — appealing.

Fernando Figueiredo, Bullet’s president, said the GPS device is activated when a shopper removes the […]