Hermione coins one of these: ‘SPEW’, standing for ‘Society, for the Promotion of Elfish Welfare’. Ron does likewise with ‘SPUG’, which stands for ‘Society for the Protection of Ugly Goblins’. A less graphic one is ‘OWL’, shorthand for ‘Ordinary Wizarding Level’, and there’s also ‘NEWTS’ for ‘Nastily Exhausting Wizarding Tests’.