While Cheetarh's response likely is sufficient to clos this thread, the OP seems like someone that needs this clearly laid out for him since he deemed it necessary to ask the question in the first place:
1) You can't leave ethics out of any decision. The fact that you request this is poff you realize this is wrong.
2) You aren't bluffing but flat out lying. Bluffing would be actually having an offer at school B, but you prefer school A, and you go to school A and tell them you are leaning towards school B because of the money and asking what school A can do. No other offer in hand isn't close to a bluff but a flat out lie.
3) Even if you are completely amoral and don't care about ethics, unfortunately for you the rest of the business world does care about ethics and tends to react poorly to unethical people. This is especially the case in business schools and in a post financial crisis business world, where there is more regulation and emphasis on corporate governance. Asking whether you can get away with something without pausing to ask SHOULD you try to get away with something is the reason we've had the Enrons, Tycos, and Worldcoms of the world. It's a great way to ruin your career or end up in jail.
4) The AdCom community is a small group. There are probably on average of 10 people per school if not less. At the top 50 schools that's 500 people. These people network, they change schools, they attend conferences. It's not hard for them to pick up the phone and call someone at another school to see if you are lying or not, and they likely would do due diligence if they were contemplating offering you money. If they then find out you are lying this could jeopardize your offer at the school to which you were admitted, would prevent you from applying to the school you used as fake leverage, and could hurt you at other schools.
5) The other four points aside, this likely won't work. If the school you are attending really really wanted you they would have offered you money. As an admitted student they want you no doubt, but chances are there is someone just as qualified on the wait list ready to fill your spot. Hell, there likely is someone just as qualified on the ding pile. Their likely reaction would be to wish you luck at the higher ranked school that offered you more money.