What does why not mean?

"Why not?" is a phrase that expresses a challenge or suggestion to do something or a rhetorical question implying that there's no good reason not to do it. It conveys a sense of openness, encouragement, and sometimes even a bit of playful defiance.

Here are some examples:

* Challenging someone: "We could go for a hike this weekend. Why not?"

* Suggesting an option: "We could try that new restaurant. Why not?"

* Rhetorical question: "It's a beautiful day. Why not go for a walk?"

The meaning of "why not?" can vary depending on the context and the tone of voice used. It can be:

* A positive suggestion: "Let's go to the beach. Why not?"

* A playful dare: "You should try bungee jumping. Why not?"

* A skeptical question: "You're going to quit your job and travel the world? Why not?"

It's important to consider the situation and the speaker's intentions to fully understand the meaning of "why not?".