We have two votes on this being an opo squash, but do we all agree? Wikipedia has no separate entry for opo squash. When searching for it, you are directed to the Calabash. Many of the images of the calabash look nothing like this, but at least one does.
You might be excited to learn that "the calabash was one of the first cultivated plants in the world grown not for food but as a container."
This squash also helped me learn once again just how small a world it is. One of our esteemed plant namers is cousin to RPCV Amanda's husband Lafi.