The worse tiny pains I've ever experienced are, in no particular order:
Catching my nipple on a door frame (it's happened when I've left a room to rush to the kitchen and taken the corner too tightly as I've gone through the door).
Going for a piss after I've been chopping chillies (it never occurs to me to wash my hands before going to the toilet, and as I'm leaving the bathroom my dick starts burning).
Choking on a chicken bone, only to have it snap and pierce the back of my throat (later it was more of an really annoying scratch rather than full on pain).
Toothache, the only pain that can wake me up or prevent me from going to sleep.
The aforementioned 'sack tap'. The last time I did this was when I'd just finished a shower and I went to rub the excess water off my chest and abdomen with a downwards motion of my hand. My hand slipped really fast and the tip of my finger flicked a ball. No immediate pain, but gut wrenching agony 10 seconds later.
Compared to those, paper-cuts, ulcers and biting my tongue are a walk in the park. I think I have a high tolerance to cutting pain and lacerations, but the internal, dull aches types of pain are horrible.