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«Μα καθόλου» can also be further intensified by «όμως», e.g. «δε σ' έχω ξεπεράσει, μα καθόλου όμως».
Other than that, when I hear «με την καμία» that Azimuthios wrote - a relatively recent variation on «με τίποτα» (no way) perhaps affected by «σε καμία περίπτωση» - that teenage "so not" springs to my mind, at least; I think they both convey the same sense of slightly bending the grammar norm to create that age group lingo.
The first time I heard "so not" in subtitling, a passing thought was the monstrous «Δεν μπορείς να φανταστείς πόσο δεν» but, with a blahblah index of 5,6+ (a ratio of 34/6, including spaces), it didn't stand a chance.