system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why did I have to throw away the lid from my water bottle going into a stadium in Hamburg?

I could keep the water and bottle but for security reasons I had to throw away the lid and have no idea why.
gpt
Removing the lid hampers the bottles ability to be used for other nefarious-type uses. It's hard to throw water bottles at the field/other team/your brother-in-law if most of the liquid and subsequent weight is removed while tossed. 

Also, removing the cap puts shame on the bottle which might make it think twice before launching itself at unsuspecting stadium goers.