It would be life-threatening to some people.. Others, mainly severe alcoholics who have built a tolerance, would just be really drunk.
Even though I'd consider myself to be an alcoholic, I think it's incredibly stupid to drink 21 shots on your birthday. At my school (UF), there's some idiot who dies of alcohol poisoning every couple months.. It's usually some dumb fvck that never drank before that tries to keep up with seasoned fratboy drinkers.
Just like any drug, people react differently. Don't be an idiot.
Oh ya.. If this is standard 80 proof liquour, you'd probby just get VERY sick (perhaps emergency room sick). If this is 120 or higher, then probby death.
And, as one more deterrant, I have drank too much alcohol on more than one occasion in my life - it usually means a night of hell for you and maybe a friend that is staying up to keep you from choking on your own vomit. One of my gf's friends from high school died that way - and that's how he's referred to. Also, I have seen people get incredibly sick because they drank a relatively small amount (a few shots in an hour) - and by incredibly sick, I mean stuff like sh!tting oneself in front of everyone while being passed out face down in one's own vomit. Oh ya, at a party I was at (but left early), I found out one of the girls I knew had to call an ambulance for some random freshman girl who drank too much. She was lying in her own sh!t and vomit while the rest of the idiots in the crowd thought it was funny. She was near death when the paramedics got to her.