Via Boston Globe:

When taunting the Republican presidential nominee, the senator goes “bawk-bawk-bawk”!

Senator Elizabeth Warren clucked like a chicken Sunday at a rally in Denver to punctuate her criticism of Donald Trump over his tax returns.

“And now, Donald Trump, the big brave Donald Trump, is too chicken to release his tax returns,” the Massachusetts Democrat said before clucking.

Trump eschewed a longstanding tradition of major party candidates releasing their tax returns, initially saying he would not do so until an audit by the Internal Revenue Service was completed. In September, he told Bill O’Reilly he would “immediately” release his tax returns if Clinton published all of the e-mails that were deleted during her time as secretary of state.