an indication that it's time for someone else to take over the parenting:

Luke: MOOOOOOOOOOOOOOOOOMMMMMMM! I want more rice!
Mom: Hey, how can you say that nicely?
Luke: MOOOOOOMMMMMMMMMY, please GIVE ME MORE RICE!
Mom: Just a sec, I'm warming it up.
Luke: MOOOOOOOOOMMMMMMMMMMMMM. MOOOOOMMMMMMMMMMYYYYYYYYYYYYYYYY.
Mom: What do you need, Luke?
Luke: I neeed more RIIIICE.
Mom: Yes, Luke, I know, but you'll have to wait one minute.
Luke: Mooooooooooommmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm.
Mom: Luke, please stop whining, or you won't get any rice.
Luke: MOOOOOOMMMMMMMYYYYYYYYYYYYYYYYYY.
Mom: Oh my GOD, Luke, what IS it?
Luke: Moooommmmmmmmmyyyyyyyy. I want some more rice.
Mom: (Getting really pissed at this point) Luke, WHAT DID I JUST SAY ABOUT THE RICE?
Luke: Uhhhhhhh.....No hitting?