Pretending is a playing the part of someone not pretending. Pretending is performing a representation of not pretending. From this it is already clear that in order to pretend something, you have to know what it means and entails to carry out the action in question sincerely or non-pretendingly. (Romeo is being original; the actor is an echo. The bear growls non-pretendingly; the child stands on all four and growls in inverted commas.). What this fact really boils down to is: Knowing how to be sincere is a necessary condition of knowing how to pretend. But it’s not a sufficient condition; acting or pretending is an extra technique that has to be learned. In other words, pretence may be done skilfully; and the criteria with which we judge such skill is connected the criteria we apply in establishing non-pretence. The skilful performance is the one which makes it the least obvious that it is pretence.
But there is also such a thing as ‘second-order-pretence’. Second-order-pretence is playing the part of someone who is playing the part of someone not playing a part. If one could not pretend in this way, no actor could do the role of someone in a Shakespearean comedy in which the very characters are often pretending to be someone else or even acting within the comedy itself. What changes in this case? The stated necessary, but not sufficient relation stills holds, but the criteria we apply in judging a performance as skilful radically changes: The second-order pretence ought to represent the first-order pretence as pretence. And to do so in an obvious manner. The skilful second-order pretence portrays the first-order pretence as bad pretence. (We know this sort of pretence from when we poke fun of some friend, who we believe was pretending in certain situation, e.g. when making an impression on someone of the opposite sex. We enact the situation token-reflexively using a squeaky voice, bad choice of words etc. in order to make it clear that this was instance of first-order pretence.) The second-order pretence must contain the first-order-pretence as a part of its representation.
There might even be such thing as third-order pretence. An example would be someone enacting a bad performance of an actor playing in Shakespearean comedy. This would an example of someone pretending to play the role of someone who is bad at pretending to be someone who is good at pretending to be someone else.