...conversation apparently started outside the restroom...
Mom (in sugary sweet voice the WHOLE time): now, Ethan, don't be like that. I want you to be a nice boy. Can you do that?
Son: No. I just want a piece of candy
Mom: I said you could, but not until after we eat something good. I don't want you to get a tummy ache.
Son: but I can have another piece?
Mom: yes, that's what I said. but not until later because I don't want you to get a tummy ache. After we eat something else you can have a piece of candy. Or a cupcake. Or Mrs. Allen made really special cookies for you. Would you like a cookie?
Son: I'd like a cookie. Can I have it now?
Mom: well, ok, but that's the last thing until after we eat some dinner.
... out the door...
UM - hello? Mom? You totally just got schnookered by your kid!