Learn Spanish (Latin America): Hago lo que quiero. ¡Ni que bebiera de cualquier vena! - I do what I want. As if I drank from just any vein!

The phrase ¡ni que! is always followed by the imperfect or past perfect subjunctive. It expresses an indignant or sarcastic rejection of an idea. Since the speaker is rejecting a hypothetical present situation (as if they drink from just any vein right now), we use the imperfect subjunctive bebiera.

Literally, what does ¡ni que bebiera! mean?

Word-for-word, it translates to something like Not even that I might drink! This does not make much sense in English, which is why it is best to memorize ¡ni que! as a fixed expression meaning As if! or It is not like! to show offended disbelief.

Why do we use lo que instead of just que in Hago lo que quiero?

We use lo que (meaning that which or what) because there is no specific noun before it that we are referring back to. If you just said Hago que quiero, it would sound incomplete. Lo que acts as a pronoun for the abstract idea of the things the speaker wants to do.

Why is it cualquier vena and not cualquiera vena?