Plonker is a word that is often used to describe someone who is foolish or silly. However, there are many synonyms for this word that can add variety to your vocabulary and help you better describe someone's behavior or personality. Some synonyms for plonker include buffoon, clown, dunce, idiot, nincompoop, nitwit, numbskull, simpleton, and dolt. Each of these words has a slightly different connotation, so it's important to choose the one that best fits the situation. For example, calling someone a buffoon might imply that they are clumsy or awkward, while calling them a simpleton might suggest that they are slow-witted or gullible.