It's a word most used by the Venezuelan people, to refer of someone or something as annoying

When you eat dirt for the first time and leave your family to build a shack in the woods

Ladilla is the spanish word for crab louse. Therefore it's usually used to reflect that someone can be as annoying as a crab louse. It can also be use in the form of a verb "ladillar". For it's sexually related content, it can also be found in expressions with such intention.

Something really annoying