Help What are these "a" pop-ups that appear on Android?

[Ravelnotch2]

I saw a lot of post about "a" pop-up on reddit softwaregore
Some says it's a XXS exploit but i could not find any answers so i can't confirm. What's going on today?

 

[mikedt]

An misconfigured or malfunctioning or infected advertising server possibly. I often look at www.thetruthaboutcars.com, I'm not seeing this strange popup in Chrome on Android.

It could be a cross site scripting problem with some compromised ad server somewhere.