5 Seconds of Summer's drummer Ashton Irwin is officially 21 today, July 7!

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The oldest 5SOS member is cracking jokes about being the only 21-year-old in the band.

On Twitter he shared a photo of himself celebrating his day of birth, which included a decorative "21" with star shaped decorations.

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"So where do I sign up for the senior benefits???" the drummer jested while also thanking all of his fans for the loving birthday wishes.

"I am a happy man!!!" he beamed. Irwin's bandmates also joined in on Twitter to celebrate the birthday boy. Michael Clifford's love for his drumming friend oozed especially with the usage of the three heart-eyed emojis.

"[C]ongratulations on being so muscular, ruggedly handsome, luscious and getting funnier every day," Clifford gushed in his birthday greetings to Irwin. Calum Hood got silly and purposely spelled his buddy's name wrong on Twitter while sharing some birthday love.

Luke Hemmings, meanwhile, got a little violent as he basically said he'll be giving Irwin 21 punches since he's now 21.

Enjoy your 21st, Ashton! You're officially the only member of the band that can legally drink in the States - Cheers!