Marshall's
I'm active in both running and cycling events, and there are frequent calls on social media for people to marshal at events. Unfortunately, the auto-carrot does seem to prefer Marshall (always capital M, so the name Marshall), so it quite often needs re-correcting, even if you've typed it in correctly. The combination of the spelling and the errant apostrophe (because adding the s makes auto-carrot think it is now something belonging to Marshall) makes me shudder to my bones.