Botellón (Spanish for "big bottle") is typically a nighttime activity when strangers get together in public places to chat, have fun and drink alcohol. This is exactly the plan for 11 May: you can join a laid-back gathering in Eiffel Square (close to Nyugati railway station). There is no entry fee, just come as you are and bring some booze too (or buy some at the bar of Zsiráf). There will be live music as well, with the line-up coming soon.