A French restaurant riddle is:
     
Q: How do you get a French waiter’s attention?
A: Start ordering in German.
   
That is, French waiters will usually ignore you—except if you are German. (Germany invaded France in World War II.) The joke as been cited in print since at least 2005.
   
     
Google Groups: alt.france
Important Information About France!
Hans Christian Andersen
7/10/05
(...)
Q: How do you get a French waiter’s attention?
A: Start ordering in German.
   
Google Groups: rec.martial-arts
Do French martial-artists fight with baguettes???
Strider
10/8/05
(...)
Q: How do you get a French waiter’s attention?
A: Start ordering in German.
 
Twitter
President Fuckface
@JRLu
@corycm @porkrind How do you get a French waiter’s attention? Start ordering in German.
1:09 PM · Apr 23, 2010·Twitter Web Client
     
Twitter
Monica Jitariuc
@MonicaJitariuc
Q: How do you get a French waiter’s attention?
A: Start ordering in German.
4:21 AM · May 18, 2010·Twitter Web Client
 
Google Books
Jokes and Targets
By Christie Davies
Bloomington, IN: Indiana University Press
2011
Pg. 104:
How do you get a French waiter’s attention?
Order in German.
 
Twitter
Bob Kostic
@causticbob
Q: How do you get a French waiter’s attention?
A: Start ordering in German.
2:07 PM · Aug 15, 2018·Twitter Web Client