What did John the Baptist call the Pharisees and Sadducees?

Answer: Brood of vipers

Seeing Pharisees and Sadducees come to his baptism, John said, 'You brood (KJV: generation) of vipers, who warned you to flee from the coming wrath?'

“But when John saw many of the Pharisees and Sadducees coming to his place of baptism, he said to them, “You brood of vipers, who warned you to flee from the coming wrath?”— Matthew 3:7 (BSB)