I haven't suffered all the above situations (I'm male, so a period is definately out). However, I think most people have suffered some of the above.
I made a
thread about dealing with gas which got some very helpful responses. Most of them dealt preemptive solutions, though--not for dealing with sudden bouts of unexpected gas like when, say, writing a uni. exam. Someone suggested Ovol, which I'll try.
For those of us who are male, an erection is a problem that crops up at the most inoppurtune times. Such as, when you're about to give a speech in front of a televised audience...
Pinching yourself into submission can help, but it's not exactly inconspicuous. And erections usually seem reluctant to go away quickly. I think they can be a natural reaction to nervousness.
I'm not female, so I can't comment on what to do when confronted with a period unexpectedly. In public school we watched a video, which suggested that you rush up and tell the teacher your problem (
) and be completely forthcoming with the problem. I'm not sure if most women would agree.
Then there are embarassing reactions to illness--coughing uncontrollably and unable to stop (very embarassing if in a uni. lecture!), sneezing all over your date, or vomiting in public--such as at an expensive restaurant, or on the Japanese Prime Minister.
I would like to hear how other people deal with these notorious, but sometimes unavoidable, situations. My general strategy has been to became less uptight, less stressed, and more educated on how the body works. What I keep telling myself is "Eveyone has suffered these problems, from the most intelligent scientist to the most regal queen. You aren't alone."