Free Comic Book Day
It shares "Ma the 4th be will you" day. I usually make this post a bit closer to the actual day, but iirc some people come into the thread and say how they missed the day? Well here is over a full week's notice. The site above will give all the details you need if you are new to FCBD. It gets bigger and bigger each year (well at the Comic shop I go to :D) and has been a fun event I've gone to for the last 4 years.