Had a similar experience with an ex-RAF fast jet guy that ended up as IRE/TRE on the Jetstream 31. We used to do base checks on the aircraft, two at a time. After my check, I got out of my (RH) seat to change with the other guy, and felt an odd sensation... turned around to see the horizon rotating in the windshield with the green bits at the top! Asked the trainer what the @#&^ he thought he was doing... "aileron rolls old chap. Perfectly safe..."
Got back on the ground and did some investigating. Turned out that this was a common occurence with this guy, but all the F/Os were so scared of losing their jobs that nobody would say anything. I thought that I should, but before I got the chance, the decision was taken away from me (thankfully). Turns out our hero had gone slightly negative G during a roll, and had emptied the contents of the toilet all over the cabin ceiling whilst inverted. Engineers saw the blue tidemark and dobbed him in, and we all had to go and testify at his disciplinary. The fleet was grounded for spar checks.
That guy lost his job, but was back training within a year (on BAC 1-11s).