Derived from the modern gaming term "hacks" or "hax". It is sandwiched in between two commonly know chatroom linguistics. "Omg" refers to the person becoming depressed or shocked in any manner. "Hax" refers to the situation or object being indescribably beyod ones imagination and "lol" is added to lighten the mood of the entire phrase.
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.