↑ baj in Johan Ernst Rietz, Svenskt dialektlexikon (1862–1867)
Etymology
Attested since 1842 as baj ("feces"), usually in the the expression fy baj, a form of reprimand used for and by small children. Johan Ernst Rietz Svenskt dialektlexikon ("Swedish dialect dictionary") also suggests[1] a relation to Middle High German baht.