The phrase "two shakes" is an idiom that typically means a very short amount of time. However, there are a variety of synonyms you can use to convey a similar meaning. For example, you could say "in a jiffy", "in a flash", or "in no time at all". Alternatively, you could opt for more playful options like "in a New York minute", "before you can say 'Jack Robinson'", or "in the blink of an eye". Regardless of which synonym you choose, the overall goal is to communicate that something will happen quickly and without delay.