débander

Débander has two very different registers: neutrally, it means for a group (troops, a crowd) to scatter or disperse in disorder — les troupes se débandent. Vulgarly and colloquially, it also means to lose an erection — a meaning that dominates in casual spoken French, so the verb needs care depending on context.

• Les soldats se sont débandés sous le feu ennemi. — The soldiers scattered under enemy fire.
• La foule s'est débandée à l'annonce de l'orage. — The crowd scattered at the announcement of the storm.
• Sans discipline, l'équipe s'est vite débandée. — Without discipline, the team quickly fell apart.

Because débander's vulgar sense (losing an erection) is so common in everyday spoken French, using the verb in its neutral military/crowd sense in casual conversation can land as an unintended double meaning — in formal or written contexts this is less of an issue, but learners should be aware of the risk.