Also, the definite form of regularly occurring nouns can also be used as a possessed noun, as something someone is supposed to have. "Jag borstar tänderna" (I brush my teeth) is a good example of this, since teeth are something that people generally have, you can replace it (mina tänder) with the definite form :).
The entire verb here is ”ta av sig” which literally means ”take off oneself” so you have to include all parts of the verb. That’s why you say ”jag tar av mig kläderna” which is literally something like ”I take off myself the clothes”. It’s not that you do it yourself, but rather that you do it from yourself rather than from someone else.
That's because it's actually of, not off. ”The taking of one's clothes.” uses of but it's too hard to try and force of into this translation to reflect that. "I will partake of some wine" uses of this way but nobody is going to say "I will take of my clothes". Another swedish phrase "ta livet av sig” would not make sense with off instead of of. It refers to the taking of one's life. So you can see it's not really off.
To start with, it should be "vad har du i fickorna?" (var = where) and "vad har du i dina fickor?" respectively.
In this case, it sounds a little bit off not including a possessive pronoun. It's like what NattKullav was asking, it could mean both.
The reason is mainly because this is a verb with a possessive pronoun in it, "att ta av sig kläderna" (to take off your clothes).