Bobby Moynihan kisses and tells. After the comic played a nerd who shares an unexpected lip lock with Allison Williams in the season finale of HBO’s “Girls,” he told us at the Summer Party on the Highline, Tuesday, “I’ve known Allison for a while. It was weird — she’s like my little sister.” But when asked if she’s a good smoocher, he added, “Of course, the greatest. [But] it wasn’t like that!” The “SNL” comic also addressed the departures of his castmates Kristen Wiig and Andy Samberg, saying of the upcoming season of the NBC show without them: “It’s all going to be in black-and-white, and there will be no sketches anymore.” Also at Coach’s old-timey, carnival-themed bash — complete with jugglers, a fortune teller, faux-moustachioed servers and special prizes from the designer — were Jessica Stam, Paz de la Huerta, Kate Mara, Maggie Gyllenhaal and Dianna Agron.