Many of these are more advanced than those described in 1 through 25 . Use your best judgement and do not attempt without a sleeping partner.
26. The Full Dog
For this, you will need a willing dog and preternatural sense of balance.
27. The Yin Yang
The Yin Yang sleeping position is two sides of the same coin - though you will need to decide with your partner which one of you is to be the evil one.