Not an intern, but this week I've unraveled some mysteries in ASP.NET MVC 5 (framework 4.8). Poked around the internals for a while, figured out how they work, and built some anti-spaghetti helpers to unravel a nested heap of intermingled C#, JavaScript, and handlebars that made my IDE puke. I emulated the Framework's design to add a Handlebars templating system that meshes with the MVC model binding, e.g.

@using (var obj = Html.HandlebarsTemplateFor(m => m.MyObject))
{
  Name: obj.TemplateFor(o => o.Name)
}

and some more shit to implement variable-length collection editors. I just wish I could show all this to someone in 2008 who might actually find it useful.