He had not been feeling so great, so he was having a Barium Series done to check for a foreign body (a blockage in his intestines).
A special liquid is given, it contains Barium - a metal radio-opaque solution, that shows up on a radiograph. Several radiographs (X-Rays) are taken over a period of time. We track the Barium flowing through the GI system.
Riddick did great, what a lover-boy! No sock this time and now he is feeling great!