caillasser

Informal/slang verb meaning to pelt with stones or rocks, built on caillasse (gravel, chunks of stone) — frequent in news coverage of urban unrest (caillasser les forces de l'ordre, caillasser un bus). Casual register, common in spoken and journalistic French about riots.

• Des jeunes ont caillassé les pompiers venus éteindre l'incendie. — Young people pelted the firefighters who came to put out the fire with stones.
• Le bus a été caillassé en pleine rue. — The bus was pelted with stones in the middle of the street.
• Ils caillassent les vitres de l'école abandonnée par ennui. — They throw stones at the windows of the abandoned school out of boredom.

Caillasser specifically implies stones/rubble as the projectile — don't confuse it with the more general lancer (to throw), which carries no such implication.

Often confused with caillouter.