When we first moved in, we had a couple of episodes of flooding in the bathroom, like a half inch of water all over the floor! When we got the super here, he tried to convince us it was due to our splashing a lot of water around when we showered and the shower curtain not fitting right. (I had it folded back so it wouldn't drag in the litter box.)
Well this weekend, both Kayakboy's sisters were here and we had the problem again. Turns out, it wasn't splashing (and no, I didn't believe that one for a second.)
Turns out, it was a ginormous clog where our apartment's plumbing meets the pipe for the rest of the building, combined with the fact that the contractors who rebuilt the place didn't install the toilet correctly. Now it's all been fixed and I think we're back in business.