The term 'toot one's horn' is an idiom which means to BOAST or BRAG about oneself. The crossword solutions for this term are 'HONK, ' 'BRAG, ' and 'BOAST.' HONK is a sound made by a car horn, but it can also be used to describe someone bragging or boasting about themselves. BRAG is another word for boasting, and BOAST is to talk proudly about oneself. All three words are related to the idiom 'toot one's horn, ' which means to BOAST or BRAG about oneself.