Sorry, Big Sean , but your girlfriend Ariana Grande is workin’ that shirt better than you ever will. The 21-year-old singer took to Instagram last night to post a sexy picture of herself sprawled out in bed while rocking her boy’s Tupac Shakur T-shirt. She captioned the black and white snapshot, “when u look cuter in his clothes than he does.” Even cuter than Ariana in that shirt? The lovefest between her and her rapper beau.