1. The opposite of a failcake.
2. A proverbial cookie served to someone who has had a major success.
3. Used to celebrate a major success.
4. In gaming speak, this is served after a player has done something worthy or skilful.
I just wiped out that entire clan in CS, where's my successcookie bitch!
My idea deserves a successcookie.
That idea is so successcookie.