Not playing with my Movie Cars

So we are trying everything possible to get CJ to use the potty and not have any accidents. Our latest resort has been to take away his favourite toy if he doesn't go poopy on the potty. This favourite toy is his Movie Cars toys.

The other night he stood in front of us as we were watching a Christmas movie and had an accident. So he lost getting to play with his Movie Cars. Shawna called to touch base and she was speaking with CJ. The conversation went something like this.

S - "CJ, what are you doing?"
C - "Not playing with my Movie Cars."

S - "Why not?"

C - "Because I pooped in my underwear and got Mater dirty."

(He was wearing Mater underwear)

With that he handed me the phone and left. So he's understanding the consequences I think he just can't be bothered. Not sure what else we can try! Agrhhhhh!!