Animals are naturally pure in their actions and some of them have these behaviors that checks off all the right ASMR triggers. For instance, monkeys are known for their social grooming or mutual grooming.
When they do this, they make sure to be gentle with their client and give them a lot of personal attention. Plus, they nibble on the bugs, dead skin and anything else they clean off their clients.
Because of this, monkey grooming creates one of the most relaxing unintentional ASMR experience.