Calvin Klein is throwing a bubbly bash at Indochine for his boyfriend Nick Gruber‘s 21st birthday. The fashion designer, 68, is buying out the entire restaurant for his young paramour, his constant companion since last year. According to a source, the invite reads: “In the spirit of the New Year and in celebration of Nick Gruber’s birthday, please join Calvin Klein for dinner and drinks at Indochine Jan. 21 at 9 p.m. It will be the hottest ticket for New York’s gay and fashion elite.” The source quipped, “Expect all of the velvet mafia to be there.”