Minecraft Quits Unexpectedly

Put the summary of the bug you're having here

I expected to play on some PvP servers!

Everytime I chatted in any of my multiplayer servers, the game quit!

Reproduce:
Log into any MC server! (I logged into mc-sabotage.com, mcctf.com, and kitpvp.us)
Type anything into the public chat.
Hit enter.
Game crashes