A lot of Australian mobile phone users have been the recipient of a premium SMS scam from the number 19900025. The message received is a really bad Christmas joke which you are charged up to $3.50 for receiving. A lot of information on the source of these messages has been uncovered at the whirlpool forums, but if you have received this message you should contact your phone company immediately to report the scam and dispute the charge. Hopefully if enough people complain quickly the scammer will be shut off before too many more people are caught.

Update: I called the number Juz gave below and left my details.  A refund cheque arrived in the mail just over a week later.