1. Daario Is Really Benjen Stark
The tinfoil on this theory is just madness. Reddit user JayisforJokes came up with this one and for a second actually had me convinced that this could really be something that's happened. What he theorizes is that when Benjen Stark went missing, he turned up in Essos as Daario to help Dany as a Tyroshi sell sword, mainly because the Tyroshi are known for their crazy hair and piercings (in the books Daario has blue hair and piercings and in the TV show he does look a bit like Benjen), which would make it the perfect disguise for him, and the fact that if he found out about Daenerys and her dragons
and the White Walkers, his big purpose could be to make sure Dany gets to Westeros unharmed. Perhaps I'm not making enough sense because there are a lot of points to this theory, but you can read the entire thread for yourself
here.
With so many crazy theories out there, it's hard to summarize what could be true and what not. Surely these are all hogwash though... right?