Some purely verbal jokes work equally well in many languages. Here is a paragraph of Chekhov’s one-page squib, “From a Retired Teacher’s Notebook”:
The words ‘proposition’ and ‘conjunction’ make schoolgirls modestly lower their eyes and blush, but the terms ‘organic’ and ‘copulative’ enable schoolboys to face the future hopefully.
(The Oxford Chekhov, tr. Ronald Hingley, Volume VI, Stories, 1892-1893, p. 260)
Here is the next paragraph, the only other one (of six) that struck me as particularly interesting:
As the vocative case and certain rare letters of the Russian alphabet are practically obsolete, teachers of Russian should in all fairness have their salaries reduced, inasmuch as this decline in cases and letters has reduced their work load.
Now you don’t have to read the whole story.
I wonder if any Latin teachers in the Middle Ages thought to ask for a pay raise when W and J and the distinction between U and V were added to the original 23-letter Latin alphabet to make the modern English set of 26 — not that that all happened at once. Actually, the development of the English alphabet was a bit more complicated than simple accretion, since the two th‘s, eth (ð) and thorn (þ), were added at some point and later subtracted, though they survive in Icelandic.