A : Hi, B.. woah, it has been long time since i met you
B : Yes
A : What are you doing here?
B : I am window shopping now. If there is good gown for next week, i'll buy it tomorrow.
A : Really? What's the event?
B : Don't you know? It's reunion.
A : Ah, i see.
B : Hey, why don't we have lunch? while we are having lunch, we can catch on.
A : Yeah, that's a good idea
B : Where do you usually eat?
A : I think, McD
B : Well, what are we waiting for? Let's go there.
A : Sure

sentences to onvite your friend, can be the other, such as:
- Would you like to have lunch? -- formal
- Will you have lunch.
- Let's eat at ..

the others are only chit chat