Pee and sneeze weirdness.

Sometimes I use the restroom when I don't really feel that I need to but I havent been in a while so I know I should go. When I sit down and focus on going I get the urge to sneeze and almost sneeze, sometimes I do. But at the same time I get this urge I am also about to pee so I'm trying to pee and not sneeze at the same time. And I guess what I am asking is what is the deal with this. Why does it happen?