Well Moxie has bitten me just playfully or cos my hands smelt like veg, and he has broken the skin, but he doesn't mean it! He's just a nibbly piggy.
But when I first introduced Meeko to Cenci and Moxie, Cenci lunged at him (out of fear) and I put my hand out and Cenci bit into my finger really hard. I automatically shook my hand and sent poor Cenci flying across the run. Then I picked up Meeko and stood up (I was in the run) and Cenci bit my foot! (I was wearing pumps and no socks.) And both of them were bleeding for ages! It hurt a lot. My dad was worried and asking if I needed to go to the doctor, but my tetanus shots are up to date and all.

I really didn't worry about it, but I was bitten badly once by a cat and in hospital for a week, so that's why my dad was worried.
And when I reintroduced Sukie and Lola, they were chasing each other around, and scared, so I went to catch Lola to take her out for a while cos they were so scared, and Lola bit me. It wasn't very deep compared to Cenci's bite, but it did bleed for a little while.
And they say guinea pigs aren't meant to bite.

I don't blame them though, cos they were scared both times they properly bit me. The moral of the story, is to wear gloves and have a tea towel ready when introducing pigs!