Stands for "Hang Out in Real Life."
Rose to popularity due to the need to differentiate between Google+ Hangouts (the group video chat option) and physical, "real-life" hanging out. Introduced by Google+ "Product
Dude" Bradley Horowitz sharing it on his Google+ stream.
Pronounced "H-I-R-
L," not "hurl."
Person 1: Alright, gonna
go hangout with
Brad.
Person 2: Wait, a G+ hangout over webcam?
Person 1: No, we're gonna HIRL at the
bar.