Rihanna performed shocking renditions of 'Don't Speak' and 'Sex On Fire', while enjoying time from her Diamonds world tour, over the weekend.
The 25-year-old pop star's embarrassing moment was shot in the early hours at the Thai Royal bar in Cologne, Germany, on Saturday, the Sun reported.
Around three security guards were stood in front of the singer to prevent bystanders from taking pictures of the stumbling star, who posed for the shocked onlookers.
Rihanna sported a baseball cap and was also joined by a female friend.
A witness told the publication that the rock star had ordered some drinks and fries for the table and then just decided to get up and sing.
The source said that Rihanna was clearly enjoying herself on her time off.