Diagrammatic techniques in statistical physics

In this talk I will try to explain on a very basic level what Feynman diagrams are and what applications they find in statistical physics. I will first stun the audience by drawing a certain QED Feynman diagram and a formula it corresponds to, then I will explain the connection between the picture and the formula, and finally in the main part of the talk I will show that similar diagrams can be used in statistical physics to perturbatively evaluate certain integrals. The whole talk will be much less advanced that it sounds, no prior knowledge of QFT is required, it will be mostly about calculating Gaussian integrals.