My old theme suggestions still apply:
Back to the roots; meta game; old school
You can also look at the previous KrassJam to get an idea of how to get your theme. Every jam is going to be different however, so you will have to wait for the jam to start to get specific instructions.
Hey there! You seem to have interpreted the jam wrong. The theme will be given randomly to you. Wait until the jam starts and you will be given instructions on how to get your theme! This is done to prevent cheating.