Calvin Klein was spotted out to dinner with two handsome men — and was so distracted he left his credit card behind. The designer, 68, dined on oysters and wine with his partner, model Nick Gruber, 21, at the Pearl Lounge at Beauty & Essex last Thursday. Nick Rytting, general manager of The Box, joined the couple before he whisked them off to the Lower East Side burlesque club. Klein, who was celebrating after his New York Fashion Week wom en’s runway show, may have been absorbed by his compan ions when he left the restaurant without his credit card. As of last night, the card was still at Pearl Lounge at Beauty & Essex, sources told us.