Some words I like

baadko(low level abuse accepted without much retaliation generally. Useful when not intending to start a battle)

laude(me personal favourite. It leaves a smooth sense of cleanliness in the mouth when you use this word)

bulle ke baal(this goes to the extreme. the hairs of the balls are supposed to be highly abusive)

Though not belonging to any place, as I have been to both hyderabad and mumbai, I would like to enlighten people with asome keywords using which you can fool people into believing you were born and brought up somewhere among the two.

Haw: A simple nod, sometimes is not understandable and yeahs and yess can take some time off when there is haw round the corner.
egjample:
Q:Are, tu kahan jaara re? DAIICT ja raha kya?
ans: haw
compact, simple and precise.

kaiku: An alternative for why, it is bound to leave the other guy flustered when you say kaiku.
egjample:
Q:mereku gharaa jaana rai.
A: kaiku?

Nakku: Dont want
egjample: teruku peapsee maangta kya?
ans: Nakku

Waich: reemphasizing on a pre-said statement
Kya bol ra miya?
Ans: waich

This is the world of how, nakku, kaiku and waich.

and then, of course there is mumbai.
patli gali se satak, line mar le, bheedo, kat and more.. you can check them up.

or check this thing I got from wikipedia
Bas kya - Don't take me for granted.
Chava or Chavi - Boyfriend/girlfriend (normally the one that is going steady).
Double battery - A person wearing prescription glasses.
Haila or Aaila - "Oh God".(the aila aila from koi mil gaya)
Paka - Irritate (literally paka means "to cook", so here the word has the sense of "cooking one's brain" to mean irritate).
Atrangi - Something strange or extraordinary.
Chappan tikkli - One with lots of pimples on his/her face.
Tapri - A road side shop.
Chotay, Tambi or Ramu - Any kid working in a tapri (small shop or eatery).
Apun - Me or myself.(One who respects himself shall never use anything other than apun to refer to the self)
Kalti- Get lost or go away.
Kaiko - Why?
Cutting - Though an English word, it is used to refer to half a glass of tea.
Some more examples...

Saalaa - Written commonly as 'sala' or 'saala'. The real meaning is brother-in-law, but is used to address a friend (Abey saale, kidhar tha? - "Where were you, dude?"), criticise/tease/naughtily refer to someone (saalaa chor - "you/that/bloody thief/prankster!!") or as an impersonal reference (Saalaa, apun ka naseebich kharaab hai! - "Hell, my fate/luck is/was bad!")
Boss - Form of address to a friend, unrelated person or stranger.
Kharcha-paani - Literally it means "stipend, pocket-money, bribe or (small) payment". In Mumbai it may also refer to beating up somebody. So depending on context, "kharcha-paani deu kya?" may mean "Do you want me/us to beat you up?" instead of "Do you want me/us to give you some money?". Conversely a person asking for a bribe (or one belonging belonging to the lowest strata when asking for some money) will say "thoda kharcha-paani do" (Give me some money).
Fultoo - Too good or very cool, not to be confused with Faltoo which means useless or waste. Fultoo may also mean drunk depending on context.
Dhakkan - Depending on context may mean "lid" or "stupid".
Dedh-dimaag - Literally "one and a half brains", in reference to an over-smart, dim-wit or stupid person.
Talli - Drunk.
Dedh-foot or Dedh-futya - Literally means "one and a half foot". Usually refers to a short person. May also be a form of irreverent address to a kid.
Chikna - Literally "clean-shaven" or "smooth". Used usually to refer to a male new-comer or teenager, especially in a negative manner.
Gadha-majoori - Literally "donkey work or labour". To signify slogging, boring or heavy work.
Tadi-paar - Means long absence, absconding, hiding or evading the police.
Mamu - Depending on context may mean a police constable or a eunuch.
Waat or Vaat - Derived from Marathi. Signifies "(to be in) trouble". Meri waat lag gayi means "I'm in trouble".
Paan-patti or Tapri - A small shop selling tobacco, cigarettes, toffees and optionally, tea.

more and more mumbaiya here