Google Search result for a website

Google is driving me crazy .!!

I have this URL: https://www.pentribe.net/shop/index.php and I was working on some SEO for it, to my surprise this is the search result on Google when I search for the word Pentribe:

Why do I have Stack Overflow as a search result ??!! And it points the homepage of the website. I'm so sure that I checked all the page headers and images' alternative text and browser page titles, but nothing changed ..!! I was also requesting re-indexing and re-crawling in the Google webmaster tools and I waited for days, but nothing is changing.

One thing more, I can see "Stack overflow" in the webmaster tools back-end, check that: I search all my website for the text "Stack%overflow" and there's nothing, not even in the database. Please help me guys before I lose my mind .!!

Thanks