The legal age for drinking in the U.S. is 21 and there has been quite a lot of coverage of people dying as a result of excessive drinking on their 21st birthday. Researchers from the University of Texas, at Austin studied 150 college students asking them how much they thought they would drink before their 21st and comparing this to how much they actually drank. The researchers found that the majority of students drank more than they thought they would and that men were more likely to underestimate their consumption than women. Drinking shots, drinking at a fast pace, celebrating with influential peers and engaging in 21st birthday traditions were all associated with drinking more than expected.
Brister, Heather A., Wetherill, Reagan R. and Fromme, Kim - Anticipated versus actual alcohol consumption during 21st birthday celebrations Journal of Studies on Alcohol and Drugs March 2010, 71(2), 180-183