A term used on 4chan's /lgbt/ board to refer to a trans person who transitioned in a range between that of a youngshit and an oldshit. The age range for this varies, but is generally between the ages of 18 and 25. Most midshits are too old to pass without surgery, but still have passing potential given enough time on hormones and potential surgical intervention.
Alice, in typical midshit fashion, simultaneously hates youngshits for being lucky enough to transition early and oldshits for existing in public.