Yeah, they prick you with a needle and inject dead TB cells just under the skin. It forms a little bump under the skin from the liquid. Then you go back in a week or so and have them look at it. If you've been exposed to TB, then you'll have lots of TB antibodies (or something) that will attack the dead cells and the area will have become all read and inflamed and stuff. Then they'll give you a REAL test to see if you've just been exposed or actually infected.
yew so smart, gondy!
*pinches