For now

So i make my living waiting tables, which is as terrible a job as it is good. Maybe? Money's good, hours are mostly good, flexibility and what not is nice, and no desk. There are of course, as in any line of work, things that drive me absolutely crazy. This is the scenario that has been getting me the most lately. And scene.
Interior of annoying restaurant with peanuts on floor (another story another time).
Customers sit down at table and stupid looking waiter (me) enters.
Stupid looking waiter: Hello customers, I'm stupid looking waiter (here in known as S.L.W.), may i start you off with something to drink?
(there are two ways this scene continues, both with the same ending)
#1
Customer: Ummm..... hmmmm... lets see (some sort of annoying thinking noise, clicking or what not) What do i want???
(or we skip all this and go straight to #2 which is what always immediately follows #1)
#2/ cont. of #1
Customer: I'll take an ice water with a lemon , for now.
S.L.W.: Okay, a water.

Why the fuck do they have to say for now? They're not gonna order anything else to fucking drink...i know this, and they know this. Why play this coy little game where i hope my sales will go up $2 more so you can give me a slightly better shitty tip? Its not like I'm not going to get the water for them if i know that's all they want.
It doesn't seem like much but deal with this at least 10 times a day everyday you work and see if it starts to bother you.
that is all