Jill is not a man.

Property just got amazing:
Professor P: “The Fair Housing Act¹ prevents discrimination based certain protected classes, including sex.”
Jack: “What about the YMCA that rents only to men?”
(Class engages in a collective ‘what the hell?’ moment.)
Professor P: “YMCAs still rent to people?”
Jack: “Yeah. I think so.”
Professor P: “Uh…well…”
Jill (frantically waves her hand): “WAIT! I just stayed at a YMCA, and I AM NOT A MAN!”

¹ 42 U.S.C. §§ 3601-3619.