I found that melting artificial sugar makes a very good glue. Take a spoon at a restaurant, and empty a packet of some fake sugar in it (might work with real sugar too, I never tried). Then put another spoon on top of it, and hold a lighter underneat. After it cools down you can't get the spoons apart. I took pity on the restaurant staff and got it hot again to take them apart. Don't know how they managed to get the gunk off the spoons though. If it does work with real sugar that would be kinder since I know that will come off if you soak it in water for a while.