Buy 6 accounts and refer 5. Then level as normal..... basically throw the 6th away. I haven't given this more than 10 seconds of thought but seems at first glance to be a way to get 5 zebras and all the rest of the benefits.

1 recruits 2 which recruits 3 which recruits 4 which recruits 5 which recruits 6.

1 Has not been recruited so you can toss it?

I have to read up on this more but what do you think?