It could be a kind of Jack O'Lantern pumpkin or cross of one to a summer squash.

George
Tahlequah, OK

It's probably a cross of something, but looks like an immature spaghetti squash to me. If there are others let them fully ripen.

Concur. Very high probability that it is a cross of some kind. Squash are promiscuous. Looks like one parent was a Grey zucchini.
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I have some of those also, I don't when to pick them or if they are summer or winter squashes. I have a lot of them though.

I tried some and it tastes like a mix between, zucchini and butternut, its pretty good. it has a buttery flavor.