Key value pairs in C# Params

When the syntax is bad for an otherwise decent pattern, change the syntax. How about:

public void MyFunction(params KeyValuePair<string, object>[] pairs)
{
    // ...
}

public static class Pairing
{
    public static KeyValuePair<string, object> Of(string key, object value)
    {
        return new KeyValuePair<string, object>(key, value);
    }
}

Usage:

MyFunction(Pairing.Of("Key1", 5), Pairing.Of("Key2", someObject));

Even more interesting would be to add an extension method to string to make it pairable:

public static KeyValuePair<string, object> PairedWith(this string key, object value)
{
    return new KeyValuePair<string, object>(key, value);
}

Usage:

MyFunction("Key1".PairedWith(5), "Key2".PairedWith(someObject));

Edit: You can also use the dictionary syntax without the generic brackets by deriving from Dictionary<,>:

public void MyFunction(MessageArgs args)
{
    // ...
}

public class MessageArgs : Dictionary<string, object>
{}

Usage:

MyFunction(new MessageArgs { { "Key1", 5 }, { "Key2", someObject } });