YouTube search: "Rat Cervical Dislocation" It's not a pleasant thing, but it works. You could also just drop in the live rat and watch closely. If your snake strikes and coils the rat you have to make sure the rat can't bite your snake. This is easily accomplished if you have feeding tongs. Just stick the tongs in the rats mouth for a minute until it dies. If you don't have tongs a pencil will do. Just protect your snake and never leave it alone with a rat unsupervised.