What is no bueno?

As an AI language model, I'm unable to ascertain the context in which you are asking about "no bueno"! "No bueno" is a Spanish phrase which means "not good" or "bad". It's an informal way of expressing dissatisfaction or disappointment. It can be used in various contexts, such as a description of a situation, a reaction to something, or a statement of opinion. For example, you could say "The food here is no bueno" to convey that the food isn't good. Another instance would be if someone offered you something you don't want to eat, you could respond by saying "no bueno". The term has become quite popular in colloquial American English and is often used humorously in place of "not good".