M.M.
My advice is to ignore it completely.
We have had this with both of my kids. The more you acknowledge it, the more they react to it. It's a way of asserting themselves and testing the independence waters.
When mine did this, I would ask them to go get clean pants and put the dirty ones in the wash pile. That's all the reaction they got. It stopped after about a week.
It will stop again, just leave everything alone.