It's talking about the shower space in the bathroom. I'm guessing the speaker means that if you wanted to attack someone in the shower, it might be difficult, because the floor would be slippery and therefore difficult to fight. There needs to be more context here. I suppose it could also be talking about a communal shower too, where the space is wider and more open, but still slippery. I'm just speculating though. Where did you pull this quote from?

It doesn't make sense.....I'm guessing its supposedly humour. the shower as a noun would be the one in tne bathroom in this case.