Analyze the emotional tone of the following tweet and classify it into one of the given categories. Possible categories are: 3: very positive emotional state can be inferred, 2: moderately positive emotional state can be inferred, 1: slightly positive emotional state can be inferred, 0: neutral or mixed emotional state can be inferred, -1: slightly negative emotional state can be inferred, -2: moderately negative emotional state can be inferred, -3: very negative emotional state can be inferred. Tweet: @Rocks_n_Ropes Can't believe how rude your cashier was today when I was returning an item!  Your customer service is slacking.
-3: very negative emotional state can be inferred