lab rat
A lab rat is a person who gets picked for experiments like they’re a piece of meat on a grill. They probably get used, abused, and then forgotten.
She’s been used in 10 experiments already. She’s got 10 different rashes and 10 different rants.
He was the test subject for the new chemical. Now he’s got a glowing skin and a new attitude.
They picked me for the experiment. I got tested, played with, and now I’m stuck with a rash and a headache.