I think I may have found the funniest Duncan/Methos series in existence.
Diana DeShaun's "The Whim Boys Series" had me laughing so hard that I was crying. It's just, I can't explain, you have to read it. And it has many many parts, which is even better. I have only read the first two yet, and they were...very very funny. And hot.
*dies laughing again*
The Whim Boy Series