3 yo peeing on the floor to punish us

This is a hard one...and I'm not sure I handled it well. I had a 4 yr old that would pee when he got mad at us. Wow, I just didn't understand that one! Def don't want to give it attention, but I did find that if he would pee on something like the bath mat I wouldn't replace it after it was washed. A few days later he would ask where it was and I would simply respond that that he could have it back when he was 'potty trained' and quickly change the subject. It would make him mad again...but I could tell he was thinking about it. After a week or two when he wasn't peeing I would quietly replace it. Oh he noticed all right. And then I would quietly take it back up if he had an 'intentional accident' even if it was somewhere else in the house. Once he started understanding cause and effect/consequences after being in our house for sometime, I then upped the anty... if he peed and we were going somewhere, I would quietly sit down and start doing something else while everyone else walked out the door. When he asked why he wasn't going, I simply said that when his mess was cleaned up we could go but I wasn't going to do it. Like I said, it's a hard one to tackle b/c you don't want to give them any indication that they have 'power' by doing it.