A few days ago i got +100 Association Bonus, does anybody know what is it? when do we get this? is there a rule or something?
You get it when you join a second site on the Stack Exchange network. If you have a certain amount of rep on the main site, you get 100 free rep points on the second sites. This way you can do things like vote right away, because you've already demonstrated that you know how the system works.