Disassemble the .NET framework to see what a method does
Yesterday I was asked if a certain method in the .NET framework returns a null. Too easy.
Downloaded and installed Lutz Roeder's .NET Reflector (wasn't installed because I'm on a new machine... normally the first thing to be installed!)
When you run it for the first time your asked to chose which version of the .NET framework you want to add.... I chose .NET 2.0
Browse to the method in question and choose to see the code disassembled into C# (or your language of choice).
Read the code for yourself.