Do you remember your first word ever?
Gak mau! = tidak mau – (I) don’t want (it)!
Some may say that girls tend to use the word ‘maybe’ (mungkin) more often. Ofc (of course, in chat form). But I think it is quite up to you, how consistent you are and when the little word ‘gak‘ may drop off to become actually just ‘mau‘ (want). Wish you luck!