When a man opens a car door for his wife, it’s either a new car or a new wife.
Prince Philip
French Knock Knock joke:
Frappe Frappe !
Qui est là?
Lorste.
Lorste qui?
Oui.
Paws for thought??
Reminds me of Lost Weekend - the film that got me into Bourbon.
In a hotel in Amsterdam by any chance?
A particular company has accused me of plagiarism.
Their words, not mine !
This has to be a french joke for Englishmen.
Anyway, I don’t get it, even if French is one of my native languages…
MArco 
Lorste qui?
Only works in English.
English children more likely.
I do not think that France has ‘frappe frappe’ jokes. In all the years of living here I have never heard (of) one. Collywobbles has provided the, er, key to the joke above. But once thought about, jokes are never funny alas.
knock knock is required by Lorste qui?
If you lost your key, you would go knock knock on the door…
Is lorste a French word? Or just one of those franglais words that sound a bit French (to an English speaker)?