I need help with a sewing project?

I'm making some tentacles, and I'd like to ultimately have suction cups on them that can stick to things; however, the suction cups I used are too smooth to hot glue. They fall off very off very easily. I also tried cutting holes to set them in, and that also didn't seem to work. What are ways I can attach them to the fabric so that they are stuck on, and won't fall off if I stick them to a window or something and pull them off? Please help soon, I want to get this done by today.