1. A state of drunkenness so pprofound that one is unable to relate to another how drunk he or she is. 2. A state of tiredness so deep that, once the person falls asleep, they are unable to be roused by any stimulus. May or may not be alcohol-caused or -related.
"D just texted me from the party and I can't read it. He's so irbunk!"
"Gabrielle was so irbunk last night that she fell asleep in our common room. I had to carry her back to her place and she slept the whole way."