Friend just collapsed like he got knocked out

[mrh86]

So me, my friend, and his brother are drinking at their house tonight. My friend and I are pretty heavy drinkers, and we're outside drinking in his garage. He gets up to go outside and take a piss, and as soon as he gets to the door, his legs collapse and he's basically out cold like somebody who just got knocked out. He hasn't drank that much yet and this has never happened before. His brother and I carried him inside, and my friend is in and out of consciousness. When he is conscious he's barely coherent. Is this serious enough to call an ambulance?