A professional dumbass is a person who does something stupid so well they aren't able to suffer any consequences.
An example of a professional dumbass:
Alix ran into battle without any weapon, once he released he had no weapon he proposed to the general. He is now a married man.
Someone or something that bites your ankles.
To a postman, an ankle biter is often known as a dog.
To an adult, an ankle biter may be a toddler.
To hikers, an ankle biter is sometimes a tick.
And so on.