Oh my goodness... my job requires me to work with a team on some fairly industry specialized software (steaming and broadcast television); the way my coworkers have their shit set up is so weird. It's like we are all speaking the same language, but with wildly different dialects.
Same, but CADD packages. Every UI is different for each app. Users each have unique configurations of buttons, ribbons, and task windows. Some apps even use completely different terms for identical concepts. Long ago I stopped remembering button and tool placement in autoCAD and just memorized commands because the GUI would completely change with every update and sometimes after a crash.