Tea for two

SUSAN:Can't you come in and have tea now, Peter?
PETER:Not yet. I must water the garden first.
SUSAN:Do you have to water it now?
PETER:I'm afraid I must. Look at it! It's terribly dry.
SUSAN:What a nuisance!
PETER:Last summer it was very dry, too. Don't you remember? I had to water it every day.
SUSAN:Well, I'll have tea by myself.
SUSAN:That was quick! Have you finished already?
PETER:Yes. Look out of the window.
SUSAN:It's raining! That means you don't need to water the garden.
PETER:That was a pleasant surprise. It means I can have tea, instead.