In America:
"Don't swim for 30 minutes after eating or you will cramp"
"You should be drinking 8 glasses of water a day"
In Korea:
"Sleeping with a fan on is dangerous as it will steal your breath"
That's a new one for me, but I'm from Europe. I spent my childhood on rivers and lakes, rapidly alternating between food and swimming (and other things). No cramps due to food (scarcely any at all to be honest). I've had a lot more cramps in swimming pools than in natural water, now that I think about it.
> "You should be drinking 8 glasses of water a day"
I could believe that. I used to drink ~4 glasses a day, but it made me feel like a lizard (without really realizing the cause at the time). Now I drink more than 8 and feel much better.
I'll add one too since its on topic with reply;
Caffeine drinks like coffee will dehydrate you. Its a diuretic but you consume more water through it then you release. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-h....