Gee I know tons of bad words in Japanese but I a would be afraid of getting banned if I started posting them. I'm talking about the kinds of words the Japanese media bleeps out.
BTW kuso l think that kuso means "shit". Here are some more ones that are on the tamer side (and ones that mostly every one knows)
baka/ahou - Both mean idiot or stupid. I think ahou is stronger than baka in Kanto but vice-versa in Kansai.
bakayaro - Is just an application of baka (yaro being a harsh very impolite way to address someone)
If you really want a comprehensive list of bad words in Japanese check out this site:
http://www.insultmonger.com/swearing/japanese.htm
I would use these with caution as you could get into a lot of trouble using these improperly. I have always found that when speaking in a language other than English (my native language) I am less inhibited in the things that I will say. I also tend to be more direct as I often don't have the vocabulary to say things delicately. This has sometimes resulted in people taking offense.
In other words don't use these words unless you are very good friends with the person you are talking with and they will understand that you are only joking or unless you really have a good understanding of the language and have a understanding of the full meaning and consequences of using them.
If you do use them there are two likely outcomes. (1) The other person will laugh at you as it sounds so ridiculous for such rude words to come from a non-native speaker. (2) They will take you seriously and try to kick your ass or never talk to you again.