Ariana Grande performs 'Problem' at iHeartRadio Music Awards + Rihanna's reaction

Last night, Ariana Grande performed her brand new single 'Problem' at the iHeartRadio Music Awards, much to Rihanna's enjoyment.

The best part of the performance wasn't even in the actual performance, which kicked off with previous hit 'The Way'. 

It was when Rihanna was caught laughing at her when she attempted to do THAT choreography. And we all know from past experience that Rihanna's reaction at award shows is entertainment itself.

The Iggy Azalea-assisted cut is a bonafide hit already as it is set to debut in the top 10 of the Billboard Hot 100 next week with over 300,000 in sales.

Thoughts?