The lecture is not related to comedy or satire, given the word "Onion" in the title. It is not a typos either, since it is "onion" and not "anion". The lecture attempts to give a feeling about how physical theories include each other forming an onion-like structure. A deeper understanding of this structure can be obtained by looking at contextuality, and information transmission/processing tasks -- e.g., zero-error information theory, non-local games, computation. Quantum mechanics, which we believe describes quite OK physical reality, appears to be sandwiched between classical mechanics and some exotic physical theories. I will show how this statement can be made quantitative.