" "Mix up" is, but doesn't fit your application. The verb usage is much more common. "He stirred up a whole bunch of ****" (pardon the vernacular).
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Clivea stir - suggests surprise, argument, confusionGreat point, Clive. "Stir" by itself (with out the "up") is a very common noun in this context. Still, it seems a bit staid for this exact case.