Task: Identify the primary emotion conveyed in the tweet and assign it to either 'neutral or no emotion' or one or more of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that best capture the tweeter's mental state.
Tweet: No red card for Gordon there? The ref must be a Celtic fan as that was a shocking challenge.
This tweet contains emotions: 
anger, anticipation, fear, surprise