Slavoj Zizek would like this joke I feel because of the lack negativity: a person in the crowd effectively declares their individuality by claiming (in Zizek's way) "I would prefer not to be an individual."

However a Lacanian critique would be that the crowd lacks knowing what their higher desires should be, so they create a sudo desire of freedom without the self exploration of what they desire to be "free for". Zizek touches on this point too that freedom requires self understanding on what you want to be responsible for: to be free is to know what is your calling beyond yourself. Without knowing your calling, freedom is either just boredom or blindly following the desires of others.