Learn Spanish (Latin America): Hizo un chiste malo sobre el chocolate amargo. - He made a bad joke about the bitter chocolate.

In Spanish, you can either hacer un chiste (make a joke) or contar un chiste (tell a joke). Using hizo here puts the focus on the action of coming up with the joke in the moment, exactly like saying "he made a bad joke" in English.

Could I put malo before the noun and say un malo chiste?

If you put it before a masculine singular noun like chiste, it drops the "o" and becomes un mal chiste. Both un chiste malo and un mal chiste are perfectly natural ways to talk about a terrible joke!

I sometimes confuse amargo and agrio. Why do we use amargo for chocolate?

Amargo means "bitter," which describes the taste of things like dark chocolate or black coffee. Agrio means "sour" or "acidic," which you would use for things like lemons or spoiled milk. So dark or bitter chocolate is always chocolate amargo.