If you make 4 contributions to FAF in October you will receive a free t-shirt.
You will receive a t-shirt from Digital Ocean which hosts the so called Hacktoberfest. Hacktoberfest is supposed to promote contributions to Open Source Software.
As a contribution counts PR that are not marked as "invalid" by the owners of a project. Contributions need to be made on GitHub.
Go to https://hacktoberfest.digitalocean.com/ to register.
There are also issues marked with a hacktoberfest lable u can get started with. But even better just ask us what u can do for example here.