blow (one's) own horn
To boast or brag about one's own abilities, skills, success, achievements, etc. I don't mean to blow my own horn, but this pasta sauce I made is quite delicious! I can't stand being around Marcus ever since his company became such a massive success. The guy just can't stop blowing his own horn!
blow one's own horn
Also, blow one's trumpet. Brag about oneself, as in Within two minutes of meeting someone new, Bill was blowing his own horn. [Late 1500s]