Lei yeh - A statement describing someone menstruating (literal meaning). This is used colloquially. (a different tone of the same pronunciation can also mean, got into deep shit, or an exclamation of shit has just hit the fan).

A more polite term is 'lei keng khei'. (for menstruation)

In slang term for menstruation, usually people will use 'tai yee ma' (literal translation - big aunty, makcik sulung). Example of usage:

"She is having her tai yee ma". "Her tai yee ma is visiting".

Also could be used to describe someone who is being too difficult.

"What is wrong with her?? Having a taiyeema??"

It's really difficult learning Mandarin or Cantonese in words, because of the tones. Different tones will bring different meaning altogether.

Hor Lin - pitiful or sympathize - depending on usage. To be used as adjective and transitive verb. eg: I can hor lin someone, and lend him a helping hand. Someone's plight can be very hor lin, and beckons for a lot of sympathy.

Chai Leong - A state of absolute sadness, dejection, bereavement, despair, sorrow (you get the idea). This is purely an adjective. Eg: A person shedding tears watching a chai leong movie. Or a state of a kid crying in a chai leong manner.

Both phrase have only slight difference when used as adjectives, otherwise, they're completely different.

Mou Ku - innocent. Pretty straight forward. Adjective only.

to give birth to a piece of barbecue pork is better than to give birth to someone like you

should be 'sang' (like sang kancil). Means, to give birth to, or grow (for objects/growth/skin disease).

the phrase you should really learn --> *** nia seng.

Actually, 'chow wa' isn't really a correct term in Cantonese to describe 'profanity'. That phrase is localized direct translation from Hokkien. The correct term should be 'Chou hau'. (literally, translates to 'impolite mouth').

Eg:
kong chou hau. (Speaks profanity)

Mm hou kong chou hau. (Do not use profanities, or mind your language).

Hok kong chou hau, lor sam yat. (Takes 3 days to learn profanities).
Hok hou yeh, lor yat sai (Takes a lifetime to learn the good stuffs).

I wouldn't use 'yiu / yew' (the meaning's more towards 'want' rather than 'need/require'). Makes you sound like a horny pornstar. LOL.

'Lor' is a better substitute, since it will make it sound like 'will take'.

eg:
Lor see kan (takes time).

chou hau = profanities. There are no rude words in Cantonese. Only informal words, formal words, profanities and rude people. :-)

"yew" is ok for different usage.

"Mm Yew" means 'don't want'.
"Mm ngoi" means 'don't love'.

Correct usage should be "Mm yew" if you want to express 'don't want'. Most Malaysians use "Mm ngoi" for 'don't want', but that's not very accurate. (Note that 'Moi' is actually derived from 'Mm ngoi' - fused to become 'Moi').
Note that this is for 'Don't want' - which itself, isn't really "polite" per se. If you want to decline something, you don't just say "don't want".

To properly decline, we usually say 'No thanks' in English. In Cantonese, it's the same lor. Just 'Mm yew' / 'Mm sai' then suffix it with a thank you (Mm Koi). It's actually quite complex. Tones and gestures also play important roles in expressing your message correctly.

Some other terms that might be useful.

"Mm chung yee" - don't like / don't love (different usage compared to Mm Ngoi)
"Mm kou heng" - displeased / not happy.
"Mm chung yew" - Not important
"Mm hou" - Not good / Don't.
"Mm phar" - Not scared
"Mm lou sat" - Not honest / dishonest
"Mm ***" (profanity) - Ignore / tidak layan
"Mm choi" (proper) - Ignore / tidak layan
"Mm koi" - please / excuse / conveying thanks
"Mm hou yee see" - Expressing embarrassment for causing an inconvenience. (not really an apology though).
"Mm sai" - 'No need' or can be used as a short form for 'You're welcome' for a thank you expression.