Adam Kirsch understood and described it very well, as I claim to be a knowledgeable person on the matter at hand.

This method exists since decades and the immediate popularly known example that comes to my mind is Daniel Cohn Bendit, a French-German politician who was a student leader during the unrest of May 1968 in France. He was also known during that time as “Dany le Rouge” (French for “Danny the Red”, because of both his politics and the color of his hair). He is currently co-president of the group European Greens–European Free Alliance in the European Parliament.

I would just add that it allows this particular breed of evangelists:

– to enjoy the opportunity to “step back” anytime arguing he was just kidding if ever things fail to turn as expected;
– to make far leftists pass as sympathetic, witty, and open-minded persons;
– to put the interlocutor, or the audience, in a state of doubt and to “soften” one’s perception of the far left as described by its detractors:
– to test the attitude of one’s interlocutor or spot/assess the positively receptive persons among an audience;

So, evangelists such as Slavoj Žižek are not kidding at all, in reality; and they can surprise their interlocutor when they happen to get more serious, eventually.

Beware!