"Toots horn" is a colloquial expression for blowing one's car horn, typically used to indicate frustration or impatience. There are several synonyms for this phrase including "blare the horn," "honk the horn," "sound the horn," and "beep the horn." These alternatives are all effective in conveying the action of activating a car horn. Other synonyms that may be used in more formal settings include "signal with the horn," "alert with the horn," and "raise the alarm with the horn." Regardless of the specific phrase chosen, the meaning is clear: the driver wants to make their presence known on the road.