Not sure how accurate the Japanese slangs you won’t find in a dictionary is. You might want to run these by your japanese speaking friends first. Here are a few words that caught my scanning eye:
chin suru: Microwave it.
dasai: It means “lame.” Commonly, it is pronounced, “dassee.” Also, combined with “cho (extra-ordinary),” you could say, “cho-dassee (extra-ordinary lame).”
iku dei: It means, “I’m going.” And you need to say it quite enthusiastically for it to sound right.
nanja korya?: It means, “What the hell is this?” It implies a deep confusion.
