Daniel Dove told the court he complied with the police up until the point he felt he was being humiliated.
"I felt embarrassed, he said. "I flicked my pants at him because I was annoyed at what he had done.
"I didn't know he (PC Birch) had a taser. He pulled it from behind his back and shot me with it. I think it was unrational (sic) to use it."
Under cross-examination Mr Dove denied being abusive and threatening club door staff. He also refuted kneeing a police officer in the groin during his arrest.
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Jeremy Corbyn's visit has been one of the big talking points of another busy day at Glastonbury.
The Labour leader said socialist politics would not be put "back in a box" as he appeared on stage at the festival.
Turning windier with a few showers