We can't believe it either, but Calum Hood is celebrating his 19th birthday today! In honor of the 5 Seconds of Summer artist's birthday (and last year as a teenager!!!!), we decided to round up some of his hottest Instagram pics of all time and marvel at his extreme cuteness!
Click through the gallery above to see some of Calum's best selfies ever. Then, make sure to wish him a happy birthday below!