As a QA Tester, can you tell me the situation when you felt the most proud of it?

When I find the defect that normally others don’t find, then I feel very proud. For example, there were situations where I found bugs that crashed the whole system at the end of testing phase. I tried the scenarios where the scenarios were NOT mentioned in the test cases. For example, we can close the windows by clicking X on the page, with “Close” button and so on. But there is another way that you can close the window, by pressing Alt+F4 on the keyboard. Not many testers test this scenario. I have done this in my last two projects. Both the time, the application crashed which became a big issue. I felt proud.