the drink is on fire. You are supposed to drink it, which puts it inside you in an oxygen free environment and the fire goes out.
you are NOT supposed to miss your mouth like an idiot, which covers you in burnign alcohol, then spit more of it out which catches fire from the flames on your face. Looks cool when you do it though.
Luckily alcohol doesn't burn particularly hot, so there's a good chance he didnlt need a new face after this.