Both ArgumentNullException and ArgumentException have a constructor which takes two strings. One is the name of the parameter (or argument) in question and the other is a string describing the exception.
The funny/odd/interesting thing about them is that one has the opposite order of arguments.
For ArgumentException the constructor is:
1: public ArgumentException(
2: string message,
3: string paramName
While for ArgumentNullException is it:
1: public ArgumentNullException(
2: string paramName,
3: string message
And my point is....
Well, I don't have one I just thought it was an interesting thing to point out :)