What's with the screaming?

All you parents out there know what the most irritating sound in the world is.  Yes--your kid screaming at the top of their lungs while you're riding in the car.  I.CAN.NOT.STAND.THIS!!!!  My son has been an expert of this since the very beginning.  He has never been a huge fan of the car and we have spent many a car ride listening to horrifying shrieks from the back seat that make you want to rip your ears off and throw them out the window. (too much?)
Fortunately, the older Bryson gets, the less frequent these deafening car rides are, however we do still have them occasionally.  Today was one of those days.  For an entire 20 minutes this child screamed his head off over who knows what.  Oh and to make matters worse, you know what he screams the whole time?  "MAAAMAAAA, MAAAAMAAA, MAAAAAMAAA!!!!!!!!!!!!!!"  Never Daddy.  Always Mama.  Ahhhh toddlers.  I'm thinking an investment in some high quality ear plugs is long overdue.