Yet another fetish I don't understand

This someone who has a Japanese Alien Egg Fetish. I'm open-minded, but I'm not sure how this works. At least you get your own oxygen mask, and that is more than most weird sexual experiments. I tried to figure out how it works, but my Japanese is too limited. If you want to ask a hooker if she will do this with you, I think you have to say: "Alien Egg Fetish o kudasai?" Anyone it seems like you crawl into this thing...and enjoy it somehow. Really its not much different than regular sex.