Oh good it's not just me.
Previously, it was standard procedure for me to middle-click any links I find in a thread I want to stay in. External links always open in new tabs but for internal ones they don't, so I made a habit of middle-clicking everything.
However, now, middle clicking external links alerts me of a pop-up. Normal clicking opens it in a new tab, but first it goes to a Geekhack URL before redirecting away.