Question: "How the hell do you...."
Answer: "Very carefully."
Seriously tho, you actually let an ELECTRIC trimmer get anywhere near yer nuts?? Brave guy!
I guess the best method depends on the type of hair you've got.
For example some here say to lather or soap up your balls (yes, they are for balance, arr arr) but I've found that makes it nearly impossible to shave them because the hair gets all soft and lays (or is it lies?) down against the skin. Not to mention mentholated shaving lather on the jewels?? I think not.
I use a regular disposible style razor (can't find anything less than twin blades these days) and shave 'em dry. Yep. If the skin isn't tight pull it tighter and shave in the direction away from where you're pulling.
Once you get 'em shaved up real nice, the easiest way is to keep 'em that way, giving them a quick pass the moment you feel any stubble. Then give 'em a glass of milk, some cookies and tuck 'em in all snuggly wuggly. Nitey night.