No doubt you also imagine the Germans strut around in jackboots, shouting "Donner und Blitzen" and "Schweinehund". After all, we all know, don't we, that the national psyche is defined by schoolboy histories of the second World War, or similar facile imagery.
For example, my idea of Americans is solely informed by fat Midwestern traffic cops.
I guess your idea could be based on a mafia don, replete with a 1940's style suit, fedora, a fat cigar in his mouth, a scar across his cheek, who speaks with a mixed Italian/ New York accent, and pushes little old ladies out of the way.
Midwest cops aren't so bad.
You have to admit that the French military accomplishments after Napoleon, a Corsican, aren't too impressive.
In the Franco-Prussian war, their emperor got captured, and France surrendered. In WW1, the Germans took a huge swathe of France, in WW2 , the Germans took all of France. Our record wasn't stellar in Viet Nam, but before us the French surrendered their entire army to the viet minh in a few weeks at dien bien phu.
In Desert Storm, the French were given objectives on the day the flanking movement began, The Americans and British met their objectives on time, the French weren't so punctual.
There are reasons why these things occurred that absolve French military leaders in these cases, the French believe.
Nevertheless, sometimes jokes are based in facts.