Also spelled "sac shot." The act of opening the fly of the pants, pulling out the nuts (leaving the soldier in the barracks), and letting 'em hang. Then approaching a seated colleague (preferably one who is preoccupied with something), positioning the protrusions directly at eye level, and asking them a question.
When they look up and see the testicle festival staring back at them, you got yourself a sack shot!
The guys on the football team would always give each other sack shots, until they found out a couple of them were enjoying them a little more than the rest.