reaction

The sweet sound of your Amazon/Postmates arriving is probably as close as we'll get. 

Rihanna reached down with the mic to let a fan sing but she obviously wasn't expecting this level of talent. Fortunately, someone caught the fan's freak out after the fact on camera as well: 

The fan in question is named Terah Jay, and apparently he's something of a singer himself. 

That face just about sums up everything, doesn't it?