The destroyers of the tea were dressed to look like indians and also professed imitate their speech they gave a "War Whoop" and the chiefs among them used an otherwise "unintelligible" mock Indian language which was then supposedly relayed to the other men aboard the ships via an interpreter. Accounts at that time noted the dialect, the "jargon" were the "most hideous Noise" that the participants in the Boston Tea Party had made. (These are all quotes from contemporary accounts.)
The blacksmith Joshua Wyeth was a participant in the Tea Party. He later remembered "We surely resembled Devils from the bottomless pit rather than men." The loyalist Peter Oliver we've agreed in his account he later wrote, "it was the Rule of Faction"— in other words it was the way of the Sons of Liberty— "to make their Agents first look like the Devil in Order to make them Act like the Devil."
— Professor Benjamin L. Carp on Resolute Men (Dressed As Mohawks) (youtube)