Task: Classify the mental state of the tweeter based on the tweet, determining if it is 'neutral or no emotion' or characterized by any of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust).
Tweet: @Rocks_n_Ropes Can't believe how rude your cashier was today when I was returning an item!  Your customer service is slacking. #terrible
This tweet contains emotions: 
anger, disgust