It only happens if you have javascript enabled.
I will tell you right now, if anyone is just willy nilly surfing around the net with javascript fully enabled, just this site giving you a popup is the least of your online worries. If you are getting a popup, you need to spend some time and learn some bare minimum, and I mean *bare* minimum computer security.
Research how to control websites access with regards to active scripting for your appropriate operating system and web browser. Just do it. Don't ask me, do your own research, too many operating systems and browsers out there. Google it up.
Me..javascript OFF, default blacklist everything, and very selective whitelisting just some domains on a temporary session basis.
I am not a professional tree climber (I like reading here and on logging though, to learn stuff), but I AM a nerd. Ignore this message if you want to....surfing with javascript totally enabled is ..hmm..appropriate analogy here... (as in what would you think if someone posted this) like joe homeowner "Hi guys! got me a big ole dead branch up in this rotten tree, guess you call it a hazard, I can climb a tree, I was a kid a long time ago! gonna take grandpappys 28 lb belchfyre magnum up there and whack that limb..no..ain't got no gear, how hard is this really? I mean just a little tree climbing with no safety line and one handing a big saw, this is doable, right?? Save me some money?? Got me a real big ole ladder,too...."
.....your call to educate yourselves or not. I have reciprocated my forum duty here and expounded on something I know something about. About all I can offer back as thanks for what I learned so far about climbing/rigging/trimming.