So, yesterday, on my day off, instead of doing a rewatch, I timelined the last three episodes in the hopes of figuring out where Dean spent his birthday this year....
Only to discover that I don't know where Dean is on his birthday in S9, because as far as I can tell, they haven't gotten there yet.
So, Happy Birthday Dean! I hope by the time your birthday rolls around, things are going better for you then they currently are...but then, this is Supernatural, so that's unlikely.
For those wondering how old Dean is, he's either 35, 37, 75, 77, or he could be 36 depending on how you view the physics of Purgatory.