Hiding money legally can get a little tricky. I don't think the Department of Education is too critical, but the IRS certainly is. You can try giving it to someone (perhaps your parents) for safe-keeping. If it were kept in a checking account that earns no interest then there were be no gains and therefore nowhere to report the gains to. If it were in your parents' savings account earning interest, the IRS might get a big suspicious about where an extra $50,000 or so came from. However, not reporting the "gift" (even if it is placed in a non-interest earning account) to the IRS is illegal but difficult to track.
Gifting money to people (over $10,000 per year) is a taxable event and the giver would owe taxes on the amount over $10,000. There is a lifetime tax-free gifting available of $1,000,000 (this is the inheritance tax thing...if you leave more than $1,000,000 to someone (actually it's $675,000 right now but will be $1,000,000 by 2006) then that money over the $1,000,000 will be taxed). The IRS is nice enough to keep track of all givfts that you give over $10,000 in your lifetime to be sure that they can get some of your money after you are dead.
So the moral of the story is, deal with the fact that if you have some substantial savings right now, you will not be eligible for subsidized loans unless you can get that money into a home before you file your FAFSA. But if you plunk that money into a home after you start medical school, then that money won't count as savings for the next year and you might then be eligible for subsidized loans. However, at the current rate of 3.46 percent (and it might even be lower for next year...they'll fix next year's rate in June) it is definitely not worth trying to do anything tricky. With a loan rate of 3.46 percent and an inflation rate of about 1.5 percent, the real cost of the money is less than 2 percent...nothing to get worked up over and probably the cheapest money you'll see in your lifetime.