In my 4 years at BYU, I heard of plenty of drinking, marijuana, sex, etc,
but never once did I hear of anyone "soaking". It's a joke that BYU students think is funny and the rest of the world takes it seriously (mostly because they WANT it to be true because they think it's funny).
I'm sure there's some random one-off cases where some illogical weirdo students have heard what soaking is and decide to do it, basically to justify "lesser sex", but that has to be few and far between.
I won't get too graphic, but think about the logistics of it, especially with a virgin female. It wouldn't be easy to accomplish.
"ask any bishop" is a cop out...it's not a real problem at all at BYU.