Christina Aguilera bought coffee for dozens of unsuspecting fans on Monday (16.02.15).

The 'Your Body' hitmaker surprised customers at Starbucks' Rockefeller Centre Concourse location in New York City and then gave the staff enough cash to buy drinks for anyone who came in before closing time.

A source said on Tuesday (17.02.15): ''Christina came in the store around 5 p.m. yesterday. There were only about 10 people in the store at first, but when people started to realise who she was more and more came in. Everyone recognised her immediately and rushed over to meet her. I'd say about 20 more people came into the store.''

The 34-year-old singer also took photographs with customers before generously leaving money to buy them drinks.

The insider told E! News: ''She took a lot of time to take pictures with the customers. She actually walked up to the register and put down some cash and said, '...anyone who comes up now until the sun comes home, it's on me.' She didn't even get herself a drink! It was really fun, It was a good time for everyone who was around.''

Shortly after the impromptu visit, the blonde beauty posted a picture of herself with a coffee cup on Instagram, captioned: ''Coffee on me for the next hour! Head to 30 Rock! XoXtina (sic).''