Fatman Scoop
Fatman Scoop and his wife Shanda at the 2008 MTV Video Music Awards in Los Angeles.REUTERS/Phil McCarten

US Hip hop star Fatman Scoop was caught on video in an impromptu performance with a busker at a London Underground station. He joined the busker, identified in local media as Juliana, in her rendition of Amy Winehouse's Valerie.

It is not clear when it took place or where. The local newspapers say it could have taken place either at Tottenham Court Road or the Bank tube station, which are intersections of the Northern and Central lines. The video was posted on Fatman Scoop's Facebook on Monday 18 January.

The star, Isaac Freeman III is known for his song Be Faithful which hit the number one in the UK and Ireland in late 2003. He took commuters by surprise as he urged them to "drop a quid in ..." as they walked by.

Initially, he started accompanying Juliana but then later took the microphone from her and started singing, while asking the busker to dance. Some of the commuters may not have known who Scoop Dog was but they certainly stopped to capture the moment on their mobile phones.

Fatman Scoop also appeared the UK's Celebrity Big Brother UK in August 2015 as a contestant. He was the third housemate to be evicted on Day 20.