Eggcorns are when a person uses a word or phrase in place of the correct one as it sounds similar. This is usually because they misheard/misinterpreted the original. Hence the name ‘eggcorns’, the correct word is acorn (the fruit of an oak tree). As you can see, they sound similar, ‘egg’ is a real word, therefore could easily be confused.
Take a look at a few examples of common eggcorns.