A: You must be hungry, it is a long time since breakfast. How about some lunch ? B: Good idea.
In the conversion , it seems that A really cares about B, actually, A is using positive politeness strategies to make his invitation being accepted.
On the other hand, the usage of positive politeness strategies is a good way to reach a consensus in the communication. The positive politeness strategies emphasizes the closeness between speaker and listener. Linguistically, the strategies will include the usage of nicknames and shared dialect or slang, even the expressions of admiration. Since people get closer, a common goal can be easily achieved. For example:
A: What lovely roses! I wish ours looked like that. How do you do it? B: Oh, you like it ? it is kind easy …
In the conversation, A is using the kind word to narrow the distance, at the same time, they reach a consensus that is they are both flower lovers.
From above, using the positive politeness strategies can easily make the request being accepted and reach a common goal, thus making the communication quite smooth going.
Now and then, the misunderstanding across cultures is so dramatic and at such an impolite level, that it is necessarily to choose the appropriate and suitable politeness strategies according to the different cultural contexts. Only in this way can we can avoid misunderstandings and make the communication more smoothly, thus promoting greater friendship in the days to come.