After Eating... Showering and swimming?

Question

1) Showering after eatting, My cousin has been told by her highschool in health class that doing this is bad.. and she explained it to me in chinese in short verison. i would like to know a long detailed article like form about why this is bad.
2) Big Movements such as swimming is bad. I know it's bad. But please explain in great details of why. I do not want a simple answer of a) causes cramps. Please explain of how it causes the cramps, like maybe because you are moving much and so, the blood is being used in other places causing this which ends up with cramps. i do not know, i'm making it up for an example. Please explain.

Next, please understand that showering after eating is not a old wives tale. and thus, i DO NOT want to hear, never heard of showering one or it's false. If it's false, why would a highschool teach it? duh.... it's real!

Do not be a cheesehead and come up with stupid cheesy answers.

about showering:
My cousin said because you a) shouldn't even do big movements [since, you're like moving up and down to shower, that is what counts as well, and thats why you wait at least 30 mins b4 swimming - to let yourself digest] and b) the hot water separates the blood from the stomache - which the stomache needs to digest.

Answer 1

You're not supposed to swim after eating because your blood is busy in your stomach not your muscles. Usually you aren't in any danger of drowning though.

Answer 2

Back in the 1040's, a newspaper in New York wrote an article where the writer said never to swim after eating, because you will get cramps, and drown. This article was based on NO facts or truth, just the opinion of the writer.

For some reason, this became FACT all across America, and then the world.

It is NOT true. You do NOT get cramps if you eat, and then swim.

Showering? Same thing. Not true. It is an old tale that became truth over the years. High school teacher heard it from others, so believed it was true also.