Nice.
The first time I shaved my balls I used a trimmer like that without any attachments covering the blades. I soon found out it would tend to pull the very thin skin on my ballsack up with hair and snip the top off to make a tiny blood volcano. It hurt a bit but was bearable.
However, I was worried about infection so naturally I did what I would do for my face and splashed on a bit of aftershave. Bad idea. Burned like fuck. Lesson learned.