How can I make my macbook pro liquid proof?
I think you are going about this the wrong way.  You are looking defensively when you should be on offense.

Consider getting something like a privacy shield to place around the urinator:



Another alternative might be to simply bring physical pain into the mix.  Wounding the urinator that sprays wildly towards you and the Macbook might make the urinator realize that control is important.

Again, think offense...not defense.