Got this feeling the cat will close this one before you learn too much but let's give it a try.

For just flat out crude, most taxi drivers/ line workers/ drunks will use:

ni ma mai pi your mothers a whore

For a slang pick-up line that makes me laugh if I hear some guy try to use it.

wo xiang gei ni da pao lit. I want to give you my big cannon

Kao - basically means F**k.

Yun, first tone... Dizzy, want to faint...

U can use it when u feel speechless...

Oh man, do you know how annoying it is when someone swears a lot in your language, and they can't really say anything else? Sometimes people run up to me and say shit like "老外! HELLO THANK YOU! ONE TWO THREE FOUR FIVE F*CK ASS BITCH", or sometimes people really want to swear with me but have no clue how to properly use the swear words, like a former student of mine "I GO SLEEP WHORE! ONLY FIFTEEN! F*CKING COOL BOOBIE OH YEAH!" Once I tangled with a dude because his girlfriend saw a white person and really really wanted to speak some English but all she knew was "Your mother is a whore." Hahahahahhahaha swearing in another language.

Best to learn the swearwords naturally, in their proper contexts. Otherwise you look like a silly c*nt.

I never teach swear words and always pull them up if my students say them. I have been asked by students to teach them, but, I explain that it not a good idea to say them as you won't make friends if you do. I teach at University level so I think they don't have a need for them. As Kchur said they are too complex. There is a lot of other things to teach rather than swear words and slang

Why would any of you assume I want to say them, let alone teach them? I want to be able to recognize them if they are being said to/about me.

Kchur, get off your high horse and stop thinking the worst about everyone. If China has made you so jaded, perhaps you should go home. You often look like a silly lil "c*nt"