Starbucks says free coffee offer started by Lady Gaga fans is fake

SEATTLE -- Starbucks is warning customers about a fake offer after Lady Gaga fans started a campaign to boost sales of her Oscar-winning song, "Shallow."

The "Shallowbucks" campaign claims Starbucks will give customers a free drink if they send a screenshot themselves listening to the song.

Some fans are even tweeting fake messages from Starbucks, saying they received a voucher for a free drink.

Starbucks says the offer is fake and that it's investigating how it was made.