Which one is the correct sentence?
a) Shall we go out for lunch?
b) Shall we go out for the lunch?
A is correct in this case.
B seems to be talking about a specific lunch; so it will need a 'that' + a restrictive clause to be correct.
We can re-write the sentence:
"Shall we go out for the lunch that features Britney Spears and President Bush?"
Don't be afraid to take a flying leap of faith.. If you risk nothing, than you gain nothing...