Odd question about the chat filter.

So recently in an end game lobby I went to bid everyone good-bye and typed 'cho cho' as I did, and it was promptly filtered into a string of asterixs. Now, testing revealed that 'cho' is fine, but not 'cho cho' and I'm just genuinely curious if I've stumbled upon a crude term I've NEVER heard of before. Can anyone help me out?
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