Contrepet, or contrepèterie, is a kind of French linguistic
joke. It consists in saying a seemingly innocuous phrase that takes a new
meaning when you exchange two sounds (consonants, vowels, even entire
syllables). "Contrepet" means "counter-flatulence" (which is hardly an
explanation).
While spoonerisms are speech errors (or pretend to be), contrepets
are often intentional and need to be carefully crafted by the
speaker. They are a kind of secret yet. When an intelligent person says
something so useless that you wonder why he said that, maybe it was
a contrepèterie, and he expects you to understand it (and
laugh). Contrepets should fit in the context of the conversation, but
few people have the talent to produce original contrepets while
speaking.
I'll give a few examples. Although contrepets are only funny when you can
understand them by yourself, I'll give the solution as hardlinks
because they require an excellent knowledge of these words
you don't learn at school. The satiric weekly newspaper Le Canard
Enchaîné publishes every week several paragraphs that comment the news
with contrepèteries.
French writers are very fond of contrepèteries. One of the oldest is
attributed to François Rabelais (16th century):
Femme folle à la messe (Woman crazy at Mass)
I once heard a colleague of mine say to a female programmer (and they
remained friends after that):
J'aime les filles qui compilent le
C (I like girls who
compile C code)
An example of double-contrepèterie (two contrepets in the same
sentence):
Quand la poule de la fermière mue, elle
vit aux champs (When the farm woman's hen moults, it lives in the
fields)
A stupid one:
Il fait beau et chaud
(The weather's fine and warm)
And one in English:
A soul full of hope
There are also unintentional contrepets, for example in the name of
Beaumont-le-Vicomte, a small city in France.