muttfluttering

The act of a dog (or dogs) putting its head outside of a moving car's window, often resulting in funny ear streaming, teeth baring and jowl flapping (or muttflap) from the impact of wind.

Look! A bulldog muttfluttering in that Ford Fiesta
Rex loves to muttflutter. He looks so funny when he starts to muttflap

by Vernon Mills January 9, 2017