Avoir une araignée au plafond is a French idiom that translates literally to “to have a spider on the ceiling” and means “to have a few screws loose” or “to have bats in the belfry”. A French definition is être un peu dérangé (to be a bit disturbed).
Avoir une araignée au plafond
to have a few screws loose, to have bats in the belfry

Example sentence
Tout le monde sait que Jean a une araignée au plafond parce qu’il n’arrête jamais de répéter les mêmes histoires.
Everybody knows Jean has a few screws loose because he never stops repeating the same stories.
Grammatical notes
- The expression tout le monde translates literally to “all the world” and means “everybody”.
- The negation ne…jamais means “never”. For example, je n’ai jamais vu (I’ve never seen).
- Arretêr means “to stop” and arretêr de + infinitive means “to stop doing something”. This lesson explains verbs followed by de.
- This lesson provides example sentences for répéter (to repeat).
- The feminine noun histoire means both story and history.
More amusing expressions
- Casser les pieds – to annoy
- Parler français comme une vache espagnole – to speak a language poorly
- Avoir la pêche – to be in high spirits
- Que dalle – absolutely nothing
- Pisser dans un violon – to waste your breath, talk to a wall
- Tomber dans les pommes – to faint, to pass out