Oop

A similar use for the word "oof", but made to sound cooler and more quirky/unique, I suppose. Usually a filler word when you don't know or care how to reply to certain comment.

Billy: "... It's like my whole life is ending. And I would appreciate some verbal feedback of a reply to let me know I can count on you as a individual human being and a good friend."

Jen: "oop"