this one worked for me but for some reason it wont work anymore:
1: log in and while it is loading click membership
2: select join now and choose your location
3:go down to the bottom and choose either a blue or purple card
4:type in the code 25832 and add 5 random numbers
5: this takes a few tries because some codes have already been used... but I guarantee it works unless moshi monsters deleted that possibility knowing a lot of people would use it...