...oh, fun!
A phrase used exclusively in female conversations which seems to translate loosely as "oh, you're bragging, and I can't stand you, or don't care."
Jill: How was your summer, Marge?
Marge: Oh, it was amazing! Bill got a huge promotion at work and took the kids and I on a fabulous European vacation!

Jill: (feigning excitement) ...oh, fun!