How to legally SUBLEASE a month-to-month without contract

[Francesco Barbati]

Long story short: 

I am renting a condo for below market value, month-to-month verbal contract from an acquaintance. I am moving out and since the landlord is very passive, lives out of state, has not time and knowledge about market rent here and I am renting below market value, I was thinking about subleasing the place and keep something in my pocket as well.

We don't have a written contract.

How do I do this legally? He is ok with that, but recently I realized that I could bump the rent up and still be below market value and keep the difference. I am worried that if I tell you he would get greedy and also he doesn't understand the involvement that renting a place require since I took care of this place and also rehabbed a little bit by-self.

Also what are the tax implications?

thanks in advance everybody!