I keep old kebab skewers. You can get about 20 on one stick, then roast them on the bonfire. ;)
Also, get 4 or 5 bigguns, line them up on the path. Then stamp on them and see how far their innards go. ;)
Failing that, cut 'em in half with secateurs and watch 'em squirm. ;)
As they don't have vertebrae, I don't think they have a nervous system and won't feel pain.