Jon Yewdell has spent most of his career in the Laboratory of Viral Diseases, NIAID, using viruses to explore how cells make proteins and how the immune system knows what they are making. His laboratory has studied proteins and peptides arising from alternative reading frames, noncanonical initiation, and defective translation. A recurring theme is that translation is messier—and more interesting—than textbook descriptions. These studies helped establish that cells translate far more of the genome than imagined and that nearly all translation products are biologically consequential, if nothing else, by providing peptides for immune surveillance. This work helped launch the exciting field of microproteins, which is demonstrating that “junk DNA” encodes more than junk, and that even the junk it encodes is interesting