There is this girl that doesn’t like me and she threatened to call Harvard Admissions Office and tell them that I got drunk at a party to ruin my chances. I’m not too worried but I was just wondering- would a phone call like that make any difference? Because I doubt Harvard would base its decisions on a call from some random teenage girl.
No lol. Even if her father was president of the united states it’d still be no.
Especially since she’s probably make the report anonymously. 
Harvard can see through this obvious sabotage attempt. There are things in life about which you might need to worry; this is not one of them.
No it will not unless it was your guidance/college counselor who reports it since getting drunk would be count as a disciplinary case.
And even then, it is highly unlikely that a GC would report this. If and when a GC files a report, it would almost always be for a serious transgression like drug dealing or hazing.
@skieurope : I think it also depends on some schools. For example, if a student get caught drunk at my school, it is a Tier 2 violation of drugs and alcohol and is a disciplinary case with serious consequences (one of them being that the incident will be reported to college)
@hola1997 Which is why I used disclaimers like “almost always.” 
However, nowhere did the OP say s/he really did get drunk or if it did occur, that it happened at the school. The GC is not going to report an incident at a private party, in general. Regardless, if a Harvard AO did get such a report, s/he’d be rolling the eyes - like freshmen in college never get drunk. At Harvard it’s a tradition for students to pee on the John Harvard statue, which usually only happens after a few beers. Again, this is not one of those things to spend time worrying about.
@richardsimpleton: Every year on College Confidential, at least one high school student writes a post like yours claiming a fellow high school student has vowed to report them to Admissions for some infraction of rules (drunkenness, cheating, stealing etc).
I’ve never heard of something like this actually happening, and even if it were to happen, Admissions would be forced to disregard the information as it would legally be considered “hearsay” (information received from other people that one cannot adequately substantiate; rumor).
Unless the offense is substantiated by a police arrest, court prosecution, or suspension from your school, Admissions will disregard any such comments if they are made. So, no worries.