Spagetti squash is labeled as such in my grocery.
To cook it, I cut off the top, then split it lenghthwise (if you have a really big one, you might have to cut it horizontally and then each half lengthwise). Scoop out the seeds. Then put in a microwaveable pan (I use a glass baking dish), cut side down, with about 1" of water in the bottom. Cover with plastic wrap and microwave until the flesh is tender. Take out and scrape the flesh with a fork the length of the squash. It'll make pasta like strings. Enjoy! It's also good added to a stir fry (cooked first as above).