Part of the vast online lexicon, ohrly? is a rhetorical question and literally means "Oh really?" It is often used, however, to imply a certain sense of sarcasm or disagreement. A refutation of a previous claim almost always proceeds ohrly?
Diat: Jank is a freakin' idiot!
Britt: I love the Jank, but dude need to use some chapstick!