Okay, so my kids aren't actually twins, but they're very close in age, and really they spend more time talking to each other than either one spends talking to anyone else. So they appear to have invented some of their own words:
bramporte: A two-wheeled vehicle such as a bicycle or motorcycle.
cracre-de-paix (or perhaps cracre d'épée?): A heavy construction vehicle.
I can't tell if these are based on real words or wholly invented, but they seem to be pronouncing them as French words, which is why I've spelled them as French words.
You can guess what types of subjects they like to discuss... ;-)
Here I am hindering them from watching the movie "Cars"