That's actually the only part of anything downstairs I do regularly shave. While growth is fairly sparse in that area to begin with, but I still keep them hairless mostly for the benefit of the wife who likes them smooth when she's doing oral and cupping and massaging them. I do have to admit they feel much better too in my hand during a solo session as well.
I always shave them at the same time as taking a bath and use just a disposable razor (at least 2 blades min.) and shaving cream. I will always go up against the grain as much like when I shave my face, it creates a much smoother surface and slower re-growth. For me it's always been effortless and I've only nicked myself once with a razor that had obviously seen too many uses for regular face shaving and was too dull. I don't think I'd ever use an electric shaver as there's just something about putting whirling or buzzing blades so close to my vital bits that makes me squeamish.
Although I've been known to go a few months without shaving them, but I try to remember to do it regularly as it helps to cut down on the itchy re-growth if it is too infrequent. Though I have found the balls are more akin to the face in that if there is any irritation it is mild compared to say the rest of the public area where re-growth can be a bitch.