Guinea pig bites are the worst.
It's not the force of the bite, although it does hurt (they bite through wood after all). It's the humiliation from having one of the most fragile, easy to kill pets decide that it can express its displeasure by biting your hand.
Damn little meat potato. The only reason you can even bite me is because you're so damn fragile I can't risk dropping you. Also, the reason I'm holding you is to trim your nails because you don't wear them down naturally since you live your entire life on padded flannel blankets. Where do you even get off having displeasure to express?
If you weren't so damn cute, you'd be on the grill.