Because that's what you're probably looking at online. Puppies, right?

Look, we've all done things that we're not proud of. Luckily for most of us, our shameful act hasn't been developed into a multi-million dollar marketing technique that pisses off countless Internet users across the world every day. (Though, if someone can figure out a way to make money from me drinking a thermos full of Ramen noodles spiked with Southern Comfort on a city bus at 3 am, I'm willing to talk.)

While writing code for back in the mid-'90s, Ethan Zuckerman was tasked with figuring out a way to allow advertisers to get their message out to consumers, but without having to splash the name of their brand name across the same web page on which some porn actor was splashing something else. And that's when an idea popped-up in his head, so to speak. And thus, the pop-up ad was born.

Sources: CNN Money