could do with (something)
One would benefit from something (which is usually stated after "with"). In this heat, I could do with a cold glass of water right now. You could do with some new shoes—those ones are looking awfully beat-up.
can do with
Also, could do with. Might profit from, needs, as in This room can do with a good cleaning, or Harry could do with a new suit. [Colloquial; late 1700s] Also see do with.