Um..porn pop ups?

Sounds like your phone may have been infected with something. It would be uncommon for a single app to have that happen. I know that it's becoming more and more of a thing where crooked people are creating scripts that are installed on devices and they'll randomly take you to websites that acquires them hits for profitability reasons.

Source: I'm a software developer and have had to deal with similar situations for a few clients over the past few months.

My recommendation would be to wipe your phone clean. It's unlikely that you'd (or anyone) would be able to find the source. After the wipe, just be careful what you click on. All it takes is going to a website that has been hacked to infect user's devices.

nope