Today is Luke Hemmings' 18th birthday! The 5 Seconds of Summer hottie has been celebrating with his bandmates all day and the guys even posted adorable and hilarious pics of him on their Twitter pages. Funny photos of Luke aren't too hard to come by, though — after all, he's always making the goofiest faces.
Click through to see 18 of Luke's most hysterical faces, then let us know which pics you love the most in the comments below. Don't forget to wish the 5SOS guy a happy birthday in the comments below.