At a Trump campaign rally in Portland, Maine Thursday, a group of protesters stood up in the middle of the auditorium and silently held up pocket booklets of the Constitution.

The move was a pointed reference to Khizr Khan’s criticism of Trump when he spoke at the Democratic National Convention, asking if Trump had ever read the Constitution as he held up a copy during his speech.

As the protesters held up the constitutions, Trump told them, “Oh, do whatever you want,” but when the audience caught on to what the action implied, they began to boo and chant, “USA”.   The protesters were quickly removed from the audience by security.