That'll be fun*

Used as a reaction to some future activity/experience that is bound to be boring, disastrous or miserable.

“Everyone in our team hates each other’s guts and now we’re going on a trip together…”

“Well, that’ll be fun…”

*Some common phrases may be used in a sarcastic way. It’s usually the context (or/and intonation) that gives away what the speaker actually means. Sarcastic words are not to be interpreted literally; they convey the opposite meaning of what seems to be said.