Non-alcoholic punch problem in american high school (or college) movies

Punch is a cocktail drink originating from India and it is served in a large bowl. It is popular in many European countries, but I think it got world wide famous through american high school / college movies where kids drink punch at parties.

In Germany we have a similar drink, a little bit more interesting I’d say. It is called Feuerzangenbowle and it is served in flames.

Punch usually contains ingredients such as: alcohol, fruit juice and, optionally, tea and spices.

In american movies, especially high school movies, there is this recurring scene with some kid pours alcohol in the non-alcoholic punch that is being served at the party. The other kids drink it and everyone gets unintentionally drunk.

The problem is that I really can’t understand how people drink something without realizing it is alcohol…

Alcohol pinches your tongue. It burns your throat. It makes you dizzy.

How come they don’t realize they are drinking an alcoholic punch?!