Here's what you need to do:
Go to your bathroom and clean it, making extra sure you clean the tub. Also make sure you have a little screen of cover for the drain. Trust me, it'll be handy. Now while your kitty dreams go out and purchase some sand, pea gravel, a trowel, a white bed sheet (assuming you don't have one), some white mice (anywhere between 2 to 4) and pinky mice (about 2 should be fine), and some wine. Make absolutely sure the mice are not the freeze dried kind or it'll ruin this.
When you get home put the mice some place where your cat can see them but not get to the. Plug the drain on your tub and put the screen in, now lay down about an inch or two of sand with some of the gravel on top. Not too much, oh, and make sure it isn't some of that painted kind. You want this to look all natural. You can even, if the mood strikes you, go to a hobby shop and pick up some plastic foliage to place in the tub. By now your cat should be awake and trying to find a way to get at the mice. Make sure you play with him to get him all riled up.
Now remember that bed sheet? Wrap it around yourself like a toga. If you have an old burger King crown you can wear that as well, but I think it's a bit tacky to do so. Now pick up your mice and place them in the tub, don't let them out of their container just yet, don't want them escaping now. Pour yourself a glass of wine. Extra points if your use a glass like the Caesers did. Now bring you cat into the bathroom. By now he should be ravenous. Release the mice into the tub and, holding you glass of wine pass sentence on them and give the word to unleash the lion. Put you cat into the tub and enjoy the show.
A few time your cat will look at you, as if asking a question. Depending on how you feel about that particular mouse he has in his jaws you can either give a thumbs up or down, but don't do a sideways one, you'll only confuse the poor dear. After you've had your fun/ the wine has run out/ the mice are dead, return any living ones to the pet shop and say they were defective. Now comes the part nobody wants to do: Cleaning up the mess. I know, a Caeser shouldn't have to sully their hands with dirty work, but this is your tub and you should always take care of your home.
Unless of course you're married, then have your servant-wife clean it.