say when

' Say when?'
'Thanks. Most awfully, most awfully
''要多少?'
'多謝--足夠了ㄅ足夠了'

Maurice by E. M. Forster ,p.40
said when you are pouring a drink for someone and you want them to tell you when to stop pouring

awful (VERY GREAT)
adjective [before noun]
very great:
I don't know an awful lot (= very much) about art, but I'm learning.
Fortunately it won't make an awful lot of difference if I don't pass the test.
It was an awful risk to take.
awfully
adverb (US INFORMAL ALSO awful)
very or extremely, when used before an adjective or adverb:
It's an awfully long time since we last saw each other.
I'm awfully sorry, but we've forgotten to reserve you a table.


(from Cambridge Advanced Learner's Dictionary)

SAY WHEN 　

　"Say when."という言い方がどんな状況で使われるか、おわかりだろうか？　これはある決まった状況でしか用いられない。誰かに飲み物を注ぐときだけ使われ る。相手に飲み物を注ぐときに、「飲みたい量まで注いだら、それで結構と言ってください」という意味で用いられる。

○Practical Example

　"Here's the mineral water, Mary. I'll pour if for you. Say when."

　 「メアリー、ほら、ミネラルウォーターだよ。注いであげるから、それでいいというところになったら言ってね」