avoir bon dos

You use this phrase when you see someone making a lazy excuse. You can use it about people, objects, or even abstract concepts like 'the economy.' It usually follows the structure: [Subject] a bon dos. If your friend blames their lateness on 'the traffic' for the fifth time this week, you might roll your eyes and say, Le trafic a bon dos ! It is snappy and effective.

Use it when you want to be a bit cheeky or skeptical. It works great when a coworker blames a computer glitch for a missed deadline. It is perfect for family dinners when your brother blames his bad grades on 'the teacher's accent.' You are essentially calling out a lie or a very convenient justification. It adds a touch of wit to your conversation.

Avoid using this in very serious or tragic situations. If someone is genuinely suffering or a major disaster happened, don't use it. It is too lighthearted and skeptical for deep grief. Also, don't use it if the excuse is actually true. If a bridge really did collapse, don't say the bridge a bon dos. You will look like a jerk.

This expression dates back to the 17th century. Back then, the 'back' was seen as the part of the body meant for carrying heavy loads. If you had a 'good back,' you could carry a lot without breaking. Over time, the metaphor shifted from physical weight to moral weight—specifically, the weight of blame and responsibility. It reflects the French love for debating and calling out hypocrisy.

You might hear avoir le dos large, which means almost the exact same thing. Both suggest that the person has plenty of space on their back to pile on more excuses. While avoir bon dos is more common for specific excuses, avoir le dos large is often used to describe a person who is constantly taking the fall for others.