The stereochemistry joke that only organic chemists will fully appreciate! The meme shows two molecules of tartaric acid with supposedly different stereochemistry - (2S,3R) and (2R,3S). But here's the twist: these are actually identical compounds! In stereochemistry, when you flip all stereocenters (S→R and R→S), you get the mirror image. But tartaric acid with (2S,3R) and (2R,3S) configurations is a meso compound - it has an internal plane of symmetry that makes it superimposable on its mirror image. So despite the different-looking names, they're literally the same molecule. The perfect chemistry prank to play on your non-stereochemistry friends!