An Etymological Dictionary of the German Language/jappen
jappen, vb., ‘to gape, pant,’ ModHG. only, prop. LG.; comp. Du. gapen, ‘to gape,’ under gaffen.
jappen, vb., ‘to gape, pant,’ ModHG. only, prop. LG.; comp. Du. gapen, ‘to gape,’ under gaffen.