guinea pig (
http://definr.com/guinea pig)
n 1: a person who is subjected to experimental or other
observational procedures; someone who is an object of
investigation; "the subjects for this investigation were
selected randomly"; "the cases that we studied were
drawn from two different communities" [syn:
subject,
case]
2: stout-bodied nearly tailless domesticated cavy; often kept
as a pet and widely used in research [syn:
Cavia cobaya]