Touching 12 volt battery terminals is indeed very, very unlikely to harm you.
However, cars are equipped with ignition coils to produce a spark for the spark plugs. When a car is running the ignition coil is producing output of 20-30 kV and back EMF in the hundreds of volts. Normally this is filtered out from the 12-volt side in order to protect the electronics and battery, but I would not recommend trusting those filters with your life.
Touching 12 volt battery terminals is indeed very, very unlikely to harm you.
However, cars are equipped with ignition coils to produce a spark for the spark plugs. When a car is running the ignition coil is producing output of 20-30 kV and back EMF in the hundreds of volts. Normally this is filtered out from the 12-volt side in order to protect the electronics and battery, but I would not recommend trusting those filters with your life.