NEW YORK (AP).- The invitation to a 1960s “happening” was intriguing: Pay $10 to enter a lottery for the chance to get a key to a Penn Station locker containing artwork. For one New Yorker who attended the 1965 event, the key revealed a Roy Lichtenstein drawing that Christie’s auction house estimates will fetch around $1 million at its May 11 auction. “Kiss V” is a study for one of Lichtenstein’s major paintings of the same name, which is in a private collection and belongs to his dream-girl series created between 1961 and 1965. Measuring 6 inches by 6 inches, the study is a comic book-inspired close-up of a man and woman, executed in graphite and wax crayon. The artist, who died in 1997, was famous for his cartoon-inspired style that helped launch — along with Andy Warhol, Jasper John and others — the pop art movement. “Happenings,