might just as well
A phrase used to discuss a hypothetical alternative that would have had results just as negative or unpleasant as what actually happened. My book report got such a bad grade that I might just as well have handed nothing in.
could/might just as well...
used to say that you/somebody would have been in the same position if you had done something else, because you got little benefit or enjoyment from what you did do: The weather was so bad we might just as well have stayed at home.