How to brain a rat

[Mephibosheth1]

Cervical Dislocation: Breaking the neck.
Put your rodent onto a flat surface, such as a table or counter. You can use something like screwdriver or stick to put behind it's neck. Push the rodent into the table with the screwdriver behind it's neck with one hand and hold onto it's tail with the other hand. Pull on the base of the tail until you feel/hear the vertebrae pop several times and the rat is dead. It takes like 2 seconds.

{I borrowed this description from an old thread, it's not my own work}

Be sure to apply determined, constant pressure to the tail while pressing down firmly with the screwdriver; it shouldn't be a jerking pull, but a strong even one.

Alternatively a CO2 tank (like used for welding) can be used to humanely asphyxiate them