There are a variety of synonyms for the phrase "toot horn," each with their own nuances and connotations. Some alternatives might include "sound the horn," "blow the horn," "honk the horn," or simply "beep." Each of these phrases may be used in slightly different contexts; for example, "honk the horn" may connote a more aggressive use of the car horn, while "beep" might suggest a more friendly or gentle sound. Regardless of which phrase you choose, however, keep in mind that using your car horn should always be done with caution and consideration for those around you.