WATCH: The Vamps Send a Birthday Surprise to Demi Lovato!
JUST ADDED: 5 Seconds of Summer will be rocking the stage at this year's iHeartRadio Music Festival Village in Las Vegas! The band sat down with Ryan Seacrest to break the news. Click here to buy your tickets now, before they sell out!
The Vamps teamed up with Demi Lovato - who turns 22 today! - in their track 'Somebody To You.' So, naturally, they couldn't help but send Demi some birthday love when they stopped by iHeartRadio today!
Could 'Happy Birthday' sound any cuter? We think not.