28th of October 2012 Halloween event. I decided to liven up the party by purchasing 150 fireworks (http://wiki.guildwars2.com/wiki/Firew...). I dropped about 80 of them so that other players could pick them up and set them off repeatedly.
It worked much better than I had envisioned, and it was an amazing sight to see.
I'm also very impressed with ANet at how stable their servers were, and my FPS, during these moments of spam.