Then I went crazy and stabbed him!
This is a video of Wil Wheaton at a panel during Denver Comic Con answering a little girl's question of how to respond to being called a nerd (SPOILER: it's not you, it's them -- they are sad). Personally, you can call me a nerd all day long and it won't hurt my feelings. Or a geek. But call me a dork and I will stab you until you're dead. Then resuscitate and kill you all over again.
Keep going for the video, then tape a 'NERD' sign on your own back for the rest of the day.