In addition to the above:
In context of this phrase "Что ты там пиздишь-то?" пиздеть has clear meaning лгать "to lie" . I'm not sure that this is what you meant. After a little bit of thinking: the same word can also be translated roughly here as "to have quite a mouth, that is just asking for trouble" But I don't think that this is what you meant either.
And to reiterate - this is highly offensive and obscene you don't want to use it in an essay.