LORELAI: That’s very Richard Simmons of you [that Luke put nutmeg in the coffee].
LUKE: Well, what can I say. Chicks dig a man with a feminine side.
Richard Simmons (born Milton Simmons in 1948) is an American fitness instructor, actor, and comedian. He ran his own gym for many years, and promoted weight-loss through exercise programs, often appearing as a guest on television chat shows.
Simmons is well known for his flamboyant, energetic personality, and his signature outfit of candy-striped short-shorts and singlet top decorated with crystals. His sexuality has long been a subject for speculation, but has never been confirmed either way.
Apparently Lorelai is just saying that putting nutmeg is coffee is “gay” (or at least sexually ambiguous). Not one of her finest moments. Luke’s comment about being a man with a feminine side may be an in-joke, as his character was originally a woman named Daisy.