Commonly mistaken to mean 'cracking the fuck up, cracks the fuck up, etc.' In reality, it means the same as 'stfu' (shut the fuck up) but 'shut' is replaced with 'chut'. Used mostly by those of Asian descent when 'chut up' isn't dramatic enough.
Boy: "I think your sneakers suck."
Girl: "Chut up!"
Boy: "Sorry, but your sneakers suck."
Girl: "I said ctfu!"