To pad the start and/or end of vacation leave with sick days.
Homer bookended his vacation to Paris, by taking a sick day to pack, and a sick day to recover from jet lag.
An irritated or active bowel, often onset by the ingestion of asian food.
Last night I had chicken teriyaki and at 2am this morning I had Wai Choon Butt and punished the toilet for 2 hours.