I use timeouts and if the little guy refused to clean up he would be sitting in a time out AND THEN cleaning it up. I am relentless with my consistency demanding appropriate behaviour and no matter how long it takes it eventually pays off.

I have had children in my care who turn into monsters as soon as they see the parents but while they are here they know that they must follow my rules. I'm honest with the parents that I have to be strict and demand things from the children because there are 5 of them against one of me but I also think they will behave better just knowing that we expect more from them. But first we have to prove to them that we won't ever cave the way their parents do sometimes.