Wat Wat has no meaning.
Now let me explain the meaning. Wat is just a suffix from the words lagaawat, banaawat, etc., which would respectively mean applies, makes. And -wat is nothing but the part of the word that decides the tense of the verb. Like -s in plays, eats and sings, like -ta hoon in khata hoon, peeta hoon in Hindi. Here the lyricist has used it nicely to rhyme a few verbs. This way of speaking where such words with -wat are used is from an Eastern UP dialect of Hindi, guess Braj bhasha.