Schnoz Full of Grey Water- Not a Fan

The kids' bathrooms are upstairs, above my bathroom. This means that each time they forget to put the shower curtain inside the tub while they shower (an honest mistake), or plug up the sink with toilet paper and leave the water running full blast and flood the house (I'm not naming names, here, but the resulting body of water was called Lake Tessa), my bathroom gets the worst of it. With their brown water stains, my ceiling tiles look like those of an inner-city crack house. I plan to replace them all, once the kids are grown. By then,  Lowe's will have had plenty of time to discontinue this particular style, and I'll have to completely redo the ceiling.
For the last month, I've noticed a new water mark on one of the tiles over the tub. Each day, it got bigger, from some leak upstairs. I asked various kids to check that there wasn't water pooling on the floor from their bathroom, but no one could find the source. It had to be from a pipe. A couple days ago, I took a picture of the wet ceiling tile and sent it to Ron.
This morning, I heard someone get in the shower upstairs and within a minute I heard the "plit-plit-plit" of water dripping onto my bathroom floor. I bolted from my bed and saw the same ceiling tile, soggy and bowed from water, dripping. I climbed up onto the edge of the tub to take a peek above the tile. I carefully lifted the edge of the tile from the metal track and lowered it about an inch. I was not prepared at all for the deluge that immediately struck my face. Between the ceiling and floor above, Ron had stapled plastic sheeting, to catch the occasional drips. This plastic had been slowly filling up, and the dampness on the ceiling tiles was merely the overflow. When I dropped the tile down, all this "grey water" rushed to the (now) free edge of the plastic, a direct hit to the face- it drained into my mouth, up my nose, into my eyes, and I fell backward off the tub and cracked my head. All I could do was lie there and watch as gallons of murky water poured from the plastic sheet funnel all over my bathroom. Some of it landed in the tub, but the majority hit the edge of the tub and splattered in every direction. And, since whomever had gotten into the shower moments earlier was still showering, the water just kept raining down.
I got up, peeled my clothes off, grabbed extra towels and threw them on the worst of it.
I sent a text to my daughter (I realize now not the most effective way of communicating with a showering person) that her shower was officially broken, and not to use it anymore.
I posted on my facebook wall, "(My daughter's) super 'neti pot' treatment has made me forget all about my cold!". My daughter's friend responded, "Use distilled water or you could get a brain eating amoeba up tharrrr, but that's probably not likely."