I recently came across this fantastic resource. It is called LINQPad.
You can use it to test any C#, F# or VB snippet or program. You can even use it to query databases in LINQ or SQL.
It's ideal if you find some code on the internet that you want to quickly test, or if you want to play with the new features in C# 6 without having to set up a windows console/forms app or website.
When I downloaded it, I pasted some code for returning whether a date is British Summer Time or not. I was able to use that code in the main void at the top and see the results instantly.
It is a free product with an option to purchase a license for more features.
So why not download it and try it out yourself and let me know how you get on.