Pair of simple English words that utterly confuse the French

Here's an example of a confusion I found yesterday:

 

Plantu's  presidential candidates both regret their years spent applying the politics of a certain "looser" (meaning a loser):
Hollande for Vals, and Sarko for Fillon.

• The verb “to lose” is extremely simple for an English child. French people are familiar with this verb. They would understand somebody who says he has lost his wallet. They recognize the sound of the word “loser”, pronounced as luzeur. They know that it designates somebody who has lost something, or has a tendency to lose things often. But they often don't know how to spell it correctly. They might even spell it incorrectly as “looser” (as in the above political drawing).

• The adjective “loose” is equally simple in the English-speaking world, because a child soon learns, say, that one of his/her teeth is loose. That child might even discover that he/she can loosen that tooth by wobbling it to and fro. In the unusual case of two teeth that are simultaneously loose, the one that wobbles more might be said to be looser than the other one. And you might have to explain to a French friend that this out-of-the-way comparative form, "looser", is pronounced as lousseur. Indeed, were the child to have three loose teeth, you might ask him/her which of the three is the loosest, pronounced louceste.

If you want to see how complicated the English language can be for a French friend, try to explain the meaning of my last two paragraphs. French people often find it difficult to grasp the distinctions between these two totally different sets of terms. If a French child found that a tooth was loose, he/she would simply say that that it moves.

For the moment, I'm not even sure I can find a common French equivalent for the adjective "loose". Suppose, for example, that I would like to say in understandable French that a certain lady has a screw loose. (Elle est givrée.) I've discovered personally that it's an incredibly difficult task! I'm not even convinced that many French people really understand the precise meaning of the saying "to have a screw loose".