Could mastubation in the shower cause someone to get pregnant if they go in (about 30 mins after) and shower,even when you let the shower on for a few minutes to wash it down the drain and use your feet and try to sweep it down the drain?
I assume that you're asking about showering after another person has ejaculated? It'd take a pretty athletic little swimmer to leap high enough from the floor of the shower cubicle to do any damage so, if that's your situation, it seems the answer is No. Even so, wouldn't it be possible for the idiot to wash it away before he leaves the shower?
But your question does have precedents.
Forty-odd years ago a young girl in South America claimed to have been a virgin yet was was pregnant. A medical examination
confirmed that she was indeed a virgin and the Catholic Church, sensing either a threat or a miracle, sent in an investigator.
The solution was simple.
The family was poor and living in primitive conditions. They took their bath in the same tub using the same water and she had bathed after her brother.
The "miracle" was dismissed but nothing is known about the brother's subsequent loss of eyesight.
This has got to be the best I've ever heard about getting pregnant but there is no way under any circumstances would this ever get anyone pregnant at all.
You're about due to have that "talk" with your parents and learn something instead of asking questions like this on here.