I don't have a middle name. My parents couldn't afford one
Don't joke about it. I told a German friend that my then girlfriend didn't have a middle name as her parents couldn't afford one and she believed me - never try to joke with Germans (MoH excepted of course).
I use my middle name, Maxwell, as I intensely dislike my first name. Both my grandads used their middle names so I'm following in a fine tradition.