"Oh, by all means," he purrs, and opens his palm to Rincewind. "Your disrespectful, casual attitude even after being corrected has definitely earned one. Mono Volt.*"
As the name suggests, this is the lesser of two electric-shock spells. Lesser as in, a direct hit doesn't actually kill people or set them on fire, which Digger Volt does. And, no, Rincewind, it's a targeted spell, so it won't burst the beach balls. But afterwards, due to static, it may make avoiding them harder. Sorry. :p