stuck in traffic? doesnt matter- youre not parked, you've got the engine running, the keys are in the ignition- this is a £200 fine and 6 points offence. If you're so bored in traffic get a motorbike then you wont be stuck and thus wont be interested in checking your facebook status likes.
Not sure if relevant for here, but male passenger in rear threw empty plastic bottle out of window into a field while in countryside of Co Donegal. Young female driver did not seem to care either.
Considerate driver.