So, when accidents happen, its usually either the car seat or the nice clean upholstery in front of the seat. And for you, as the driver, you can only do two things:
1) Open the window and hope they can hold it (too bad if yours is the wind-down)
2) Open the car door and kick them out. (Ha ha ha)
This is the "bucket" type of rubber floor mat which contains all the nasty liquid
And it sits nicely under other unecessary carpets in the car
(OK, I don't want to throw them out)
But stinks sky high of rubber if brand new
So, with that rubber mat, you now have the third option:
Hold them by the neck and push forward where they can do what they want on the rubber mat. Of course, make sure you are able to switch gears as well. Once you have stopped the car and they are outside their front door, take the rubber mat out and return the nasty liquid by pouring on their head. Ha ha ha ha