This meme is fucking intelligent. Let's remember the importance of Marx in the construction of the human thinking (disregarding here the socialist/laborite stuff), that is: Marx was the most prominent anti-hegelian philosopher.
Hegel was an idealist, this means that the wisdom is acquired through thoughts, idealism, these were the keys for the knowledge. The reason was found in the ideas' world. Personally and analogously, I link the Hegelian ideas' world to the Plato's intelligible world.
But what Marx said? Marx minted the praxis, so the wisdom is no longer in the ideas' world, it is necessary a practical simultaneous action to acquire it ("Proletarians of all countries, unite!")
Namely this is the context of the meme, Hegel discoursing about the idealism and Marx calling him a boomer ("where's the praxis, boomer?" )