steal somebody's thunder
steal (one's) thunder
1. To garner the attention or praise that one had been expecting or receiving for some accomplishment, announcement, etc. My brother is the star athlete of our high school, so no matter what I succeed in, he's constantly stealing my thunder. We were about to announce our engagement when Jeff and Tina stole our thunder and revealed that they were going to have a baby.
2. To steal one's idea, plan, or intellectual property and use it for profit or some benefit. We had the idea for "digital paper" years ago, but I see they've stolen our thunder and have their own version of it on the market.