"Blowing your own trumpet" is saying good things about yourself so that others can hear about you. Example: "Is Deb still talking about the deal she made?" Reply: "Yes, she's blowing her own trumpet."

"Blowing your own trumpet" is talking about what you have done so others will know how good you are. Example: "Don't listen to him. He's just blowing his own trumpet." Another example: "There you go again, blowing your own trumpet."