(AP)—Don't scream for ice cream. Just pick up your smartphone.

Uber, the San Francisco startup known for letting people order private drivers in sleek black cars using a app, is offering an -on-demand service for one day only in more than three dozen cities around the world, including San Francisco, Philadelphia, London, Singapore and Rome.

Friday's stunt, an expansion of last year's ice cream promotion, comes in the midst of a sticky heat wave in New York City and elsewhere. Last year, people in seven U.S. and Canadian cities could use the Uber app to summon an ice cream truck hired by Uber to their location, provided they purchased a minimum number of treats. But demand exceeded supply, and not everyone who wanted ice cream got it.