Ask you a question, to which he already knows the answer will be 'No', just to start an argument?
DS does this fairly often. Take this morning for example. We get in the car to go to school, and he says "if I do my homework and guitar practice without fuss this afternoon, can I go on Roblox(a computer game) tonight?"
Now we have banned roblox after several warnings, because whenever he has been playing it he comes off the computer grumpy and un-cooperative. So we have blocked the site completely.
So I said "no, it's been blocked because it makes you irritable, as you know".
Then he whines for 5 mins about us being mean, stopping him doing anything he enjoys .... blah ...blah.
Then after 2 minutes of quiet (after I've yelled "I don't want to hear any more about Roblox") he says ....... "how long is it banned for, can I play it again when I'm 10 ?"
AAAAAAAARGH.