Browch was first introduced on the Adam Sandler movie, "Just Go With It." It appeared to be someone who had a "loose" eyebrow, one slightly elevated from the other eyebrow. However, more recently this word is being used as a combination of "ouch" but with your eyebrow raised therefore you would say "browch."
Wow dude, "browch." I didn't see that coming. You were really rude, (with your eyebrow) raised.