Nina Conti is a brilliant ventriloquist who uses "live" dummies in her shows. By placing a mouthpiece on an audience member (which she can control to make it look like the audience member is speaking), she can make it seem like the audience member is part of her show.
But this is where it gets interesting: audience members are often reluctant to do things she asks them to do and their body language clearly shows this hesitation. Nina, however, uses certain phrases and tones when "throwing" her voice that make her "dummy" appear to be fully and eagerly cooperating with her requests. The way in which these phrases and tones are used suggests that the body language is actually stating the opposite of what is intended. See this presentation below. Though all of the audience member's gestures are those of hesitation and non-cooperation, they look the opposite.