The original meaning word by word would be, don't laugh. But in Korean slang, it's defined as, bullshit!(but not known as profanity) or Yeah right!(sarcasm). If someone were give you a bogus story, you would say, Oot-ggi-ji-mah!
as in "don't make me laugh"... Comment by: B
웃기지마 means "Don't make me
laugh." Comment by: Andrew