Adjective describing a less than sincere and slightly pained but polite expression of liking or enjoying something.
Chick serving food on a first date to a dude she digs: "I hope you like hummus."
Dude who hates hummus but likes chick: "Sure, hummus is fine."
Dude's response was hummusy (insincere, slightly pained, but polite).
Adoring mother: "I hope you like the phone-book cozy I knitted for you."
Adoring mother's mortified kid: "Yea, it's nice."
Adoring mother: "I'm sensing a hummusy tone. If you don't like it, just say so (you ungrateful prick)."