Hacktoberfest is an open source collaboration between GitHub, Digital Ocean, and this year Twillio. The aim is to give back to the open source community by encouraging more developers to get involved and open some pull requests. Each developer who signs up to take part get some fancy laptop stickers and those who complete 5 pull requests get a free tee shirt!
This is the fith year of Hacktoberfest and there are 50, 000 shirts up for grabs this year. There's still plenty of time to get involed and earn your tee shirt.