Oh my kids and I had a guinea pig once. It was so cute and cuddly. We would get it those alfafa blocks and it loved them. Sometimes we'd give them a little grass from outside or clover..not a lot. He loved lettuce and grapes. Be sure to watch his front teeth. They can grow so long they cannot eat and will starve to death. Ours would not use the chew blocks and the vet had to file his teeth.
No one could open the refrigerator without hearing the little cheep cheep because he knew his food was in there.
Good luck they make great pets.