Olives for motion sickness
Motion sickness is accompanied by increased salivation, which is the body's way of protecting teeth from stomach acid in the event of vomiting. Olives contain tannins, which dry the mouth out, so eating a few can eliminate the excess saliva. Treating that symptom can reduce nausea and keep the body from vomiting.
The key is to eat the olives as soon as the first waves of motion sickness hit.