Football fans tend to like a beer. That's why FIFA insisted that Brazil's law banning alcohol from stadiums was overturned—which it was, in 2012.
Accordingly, if you leave beer unattended in a stadium, as it was during Mexico's opening match against Cameroon, you can safely expect fans to take it and drink it.
The 27-second clip above shows you the joy that free beer can bring.
[YouTube, h/t Dirty Tackle]