[sublime]

simple answer

call and reschedule his flight
call the desk and book the room an extra night

then

if you dont have any pressing matters at home, suck it up and change YOUR flight (at his expense, whether or not you can afford it is irrelevnet)

or

pay a 2+2er to watch him for the next 6 hours. wake him up after 3 hours and force him to drink a lot of water, then again after another 3. again, ggban pays for this.

do NOT inform the casion like someone suggested. they will call the police who will then take him to a hospital.

who the [censored] counts how drinks they have had?