say when

Say when.

Inf. Tell me when I have given you enough of something, usually a liquid. (Sometimes answered simply with When.) Tom (pouring milk into Fred's glass): Say when, Fred. Fred: When. John: Do you want some more juice? Mary: Yes. John: Okay. Say when.
See also: say

say when

to stop or end something Should it continue forever? When do you say when?
See also: say