لا تفعل هذا

The phrase changes slightly based on who you are talking to. For a man, say ماتعملش كده (Ma-te'melsh keda). For a woman, add an 'i' sound: ماتعمليش كده (Ma-te'melish keda). If you are talking to a group, use ماتعملوش كده (Ma-te'melush keda). It is very flexible. You can add لو سمحت (please) to soften the blow. Or add تاني (again) if they keep repeating the mistake.

Use it with friends when they make a bad joke. Use it with siblings who are being annoying. It is perfect for parenting or teaching. If a colleague is clicking their pen too loudly, this works. In a taxi, if the driver takes a wrong turn, you might use it. It is the ultimate 'stop it' button for daily life.

Avoid using this with your boss in a high-stakes meeting. It might sound a bit too blunt or childish. Don't use it with elderly strangers unless they are doing something dangerous. In very formal settings, Modern Standard Arabic is better. Using it with a stern face can seem aggressive. Always check your tone before speaking.

Egyptians are known for being expressive and direct. The 'Ma...sh' negation is a unique feature of the Egyptian dialect. It likely has roots in the ancient Coptic language. When you say this, you might see the 'Egyptian finger wag.' People often shake their index finger side-to-side while saying it. It adds a layer of 'I am serious, stop it' to the phrase.

You might hear بلاش تعمل كده (Balash te'mel keda). This is a slightly softer, more 'advisory' version. Another one is اوعى تعمل كده (O'a te'mel keda). This is a strong warning, like 'Don't you dare do that.' If someone is saying something wrong, use ماتقولش كده (Don't say that). Each variation adds a different spice to the conversation.