First, make sure your bum is clean and dry. Second, get a hair trimmer and spread your cheeks a little to get all the hairs. I’d recommend this hair trimmer that can also be used for ear and nose hairs. Philips NT5175/49 Norelco Nose trimmer 5100 Facial Hair Precision Trimmer for Men https://www.amazon.com/dp/B00QYOSKH6/ref=cm_sw_r_cp_api_i_zq6dBb5RA3DAT
I would say leave them as they are...
If you really want to "trim" them, look into this
Don’t listen to these other comments!!! I used to have AWFUL skin from using shaving gel / Gillette razors. I now have flawlessly smooth skin.
I use this electric trimmer on my neck/ face : https://www.amazon.com/Philips-Norelco-Eyebrow-NT5175-49/dp/B00QYOSKH6/ref=mp_s_a_1_12?keywords=philips+trimmer&qid=1563218014&s=gateway&sr=8-12
And sometimes I use this trimmer on my face (as long as I don’t go too aggressive I don’t get bumps): https://www.amazon.com/Panasonic-Electric-ES8103S-Nanotech-Flexible/dp/B001DNE3KQ/ref=mp_s_a_1_4?keywords=panasonic+electric+shavers+for+men&qid=1563218118&s=gateway&sprefix=panasonic+ele&sr=8-4
That is IT. Don’t shave when your skin is wet / don’t use shaving cream. That gives you too close of a shave, thus leading to bumps. Always shave DRY.
I was a very severe case of bumps and the combo above has worked perfectly
Edit: with the second electric shaver, you can even shave over existing bumps and they won’t bleed. It gives you as close of a shave as a manual razor but it will not leave a rash. Don’t use it on your neck if that’s a problem area
This is what you want.
https://www.amazon.com/Philips-NT5175-49-Norelco-Precision/dp/B00QYOSKH6?th=1
I used to blade shave my arms regularly, usually when the razor blade I was using on my face was ready to be retired, I'd run it over my arms, then change for a new one.
Recently I purchased a small battery operated trimmer for ear, nose and eyebrows, and the trimmer attachment is just about perfect for mowing down arm-hairs... and I don't have to worry about nicking myself on the wrist bones.
Yep, that is what I meant. I have both kinds. The linear kind commits jihad in my nose. Not only that, it's awfully ineffective.