Well, jouluposti has multiple uses. It literally means christmas post.
The word jouluposti are commonly used when talking about
1) The letters kids usually sent to santa claus
2) A retarded tv-program in finnish television during christmas. You can send your "christmas greetings" by sending a text message or calling to the program's number. The show's audience usually consists of teens who seem to love wasting they're money. The show is also famous for being a target to prank callers and hackers. Jouluposti
There are also many other shows like the one I mentioned. For example "Santa claus' hot line", which airs on the morning of christmas eve.
That's all I can think of for now. IS THIS OK FOR YOU? ;<