Having sexual intercourse; term is used to state when someone, or them selves are having sexual intercourse with another person, and not caring when and where they are having sexual intercourse.
Guy 1: "What did the neighbors do last night? I could hear them outside!"
Guy 2: "They were outside, pulling a Ky."
Guy 1: "But they don't have a picket fence up !"
Guy 2: "yup."