M.S.
I know you all may laugh at this but my son who is also 2 1/2 loves to pee outside in our backyard. We spent a week with my nephew, who lives on two acres and can get away with it . . . and my son picked it up. While it can be embarassing it is working. He does go in the potty but also will just wander outside, pull his pants down and pee :) He is a boy and is going slower than my daughter did but I heard boys were harder to potty train. I agree with Rachel, he will regress so don't push it and let him go at his own pace. Wish I had better advice as I am going through the same thing. Be as patient as you can. Good luck!