You shouldn't drink before you're allowed to do it (obviously) and I even think that the minimum age of 16 in Germany is too low. Alcohol is, as I already stated, a neurotoxin and it can destroy your brain and it can even kill you. Moreover you may accidentally cause damage to others while being drunk as you can lose all control over yourself.
Being very drunk is a bad thing and feeling bad the next day is a clear indicator that you did something wrong and that you should drink less or maybe no alcohol at all.
Cool and smart people either don't drink at all or they drink responsibly and stop at the right moment.