The title kind of says it all. I was thinking about a story I'm writing and part of the plot is that one of the characters gets "drugged" without knowing it. Imagine if someone was a football player and someone spikes his drink with something that just makes him feel bad. Bad enough to have a bad game, but not bad enough to require a doctor or make anyone too suspicious that something might be going on. I thought of using something like a laxative, but I don't know if that's the sort of discomfort I'm looking for and I'd think that it might be too obvious.