Katy Perry was serenaded by 14,000 fans during a show in Belfast, Northern Ireland on Monday (24Oct11) as they sang Happy Birthday to the star.
The I Kissed a Girl hitmaker turns 27 on Tuesday (25Oct11), and she took to the stage at the city's Odyssey Arena on the eve of her big day.
During a break in the set, the audience sang to the birthday girl and her dancers brought on a colourful cake, which Perry shared with her fans by hurling it into the crowd.
She said, "Thank you so much, I wouldn't have it any other way than celebrating with you!"