Level: B1 (intermediate)
The French word of the day is: Déconner (slang), meaning to act like an idiot, do something stupid and to mess around. This verb is related to the slang (offensive!) adjective con, meaning “stupid” or “dumb”.
déconner – IPA pronunciation [de.kɔ.ne]
“Déconner”: A Great French Slang Verb To Add To Your Vocab List

Déconner example sentences
Arrête de déconner et essaie d’écouter ce que je suis en train de dire !
Stop messing around and try to listen to what I’m saying!
This first example sentence uses the expression être en train de, which is used for expressing the progressive present (verb+ing) tense.
Tu déconnes ou quoi ? Sois serieux pour une fois !
Are you kidding around? Be serious for once in your life.
Sois (be!) is the imperative form (commanding tense) of the verb être (to be). “Ou quoi“ translates literally to “or what”. We added “in your life” as a loose translation.
Ah zut, la tablette déconne encore !
Ah shoot! The tablet is acting up again!
Another meaning of déconner is “to act up” or “to play up”, implying to not function correctly. This word of the day lesson covers “zut !” (shoot, darn) and this lesson covers encore (still, again, yet).
Continue learning French!
Two more commonly used slang verb that’s worth looking into are bosser (to work hard) and bouffer (to eat). This lesson provides a wonderful overview of French slang.