How about is an informal invitation. How about a coffee means
1. Would you like some coffee? or
2. Let's have coffee together.
The following is an invitation to reconsider something.
How about revisiting the logic we used in deciding that. We may have made a mistake somewhere.
It can also be an exclamation indicating surprise or approval. How about those Yankees might be said by one baseball fan to another if the Yankees had recently performed well.