One want to ask a question in regard to a person's suggestion to contribute:
Tina: "You should get laid more than once a year"
Tom: "the best you could say?
should I use can or could?
I can't really come up with any form involving "the best you could say" that sounds at all like something a native speaker would say. Depending on what exactly you're trying to get across, one of the following might be appropriate: