Donald went to a well known adult site on her iPhone, and now he believes his phone is infected. He gets a popup that says "call for Apple support" and they want $35 to fix it. Leo says it's not usually possible to hack the iPhone, so it may be a modified Safari home page instead.
Donald should go to the settings and make sure it's set to a benign home page like Google. While there, he should clear his history and website data. Then reload and see if it pops up. He should also turn on 'block cookies.' That should solve it. He can also install another browser like Chrome and see if he can replicate the problem. If not, then it's an issue in Safari and clearing the cache should fix it.
If none of that works, he can always do a factory reset.