Is sitting within wet while on your interval dicey?

My grandma (R.I.P) used to tell me that if you sit within water while on your interval it could cause cramps. Does it produce cramps or make them worse? Kiara, I own never heard of anything approaching this ever and I am 33 years old. I would do a google go through on it if I were you, but I don't come up with water hurts you or cause cramps at all. If anything I would have a sneaking suspicion that that it would calm you and your cramps down during your spell.
No, its an old wives parable. A warm hip bath can make cramps better.