Blow your own trumpet
Definition 1 of 1
Pro Tip 1/3Self-Praise Focus
The phrase implies praising oneself, usually excessively and not appreciated by others. 
He's good at math, but he shouldn't blow his own trumpet every chance he gets.
Pro Tip 2/3Informal Context
Used in casual conversations among friends or colleagues, but not in formal settings. 
At the reunion, Jim was blowing his own trumpet about his new business venture.
Pro Tip 3/3Perceived Negativity
Often viewed negatively, as it can seem arrogant or lacking humility. 
Even though Lisa volunteered successfully, people were turned off by her blowing her own trumpet.