Honestly with pinkies or fuzzies it is just easier to break their necks... its an instant kill and they wont feel pain... also for the smaller ones if you dont want to break anything or smack them you can put them in a plastic bag (sometimes double bagging them) and put them in the freezer.. their body is slowed down so much they dont feel much pain at all... if you dont want to keep them you can just toss them after that... your call... hope this helps
I thought rapid freezing bursts blood vessles causing immense amounts of pain?