Can i bring alcohol in my checked luggage on a plane?

I am 15 and i was thinking about bringing vodka in a water bottle and putting it in my checked luggage. will i get in trouble because i am underage or will they not care since they dont have proof that i drank any of it? and please dont give me a long lecture about how "its bad to drink etc etc"

There are several things to consider:
Where are you going? Are you leaving the country or staying in the country? Will they check liquids in checked baggage? Will they care if they find it?
First, yes, they can and do check liquids in checked luggage. Although larger quantities are allowed in your checked luggage they will still x-ray and inspect liquids contained in there. This is true even if your luggage is locked as all luggage have master keys/codes available to people working at these points. If you location a noncomplying lock on your case they will simply cut it off.
If they find vodka in a water bottle they will confiscate it and you could face charges related to smuggling. If, however, they find vodka in a vodka bottle the worst that will probably happen is confiscation and a lecture (assuming the bottle is still sealed).
If you are leaving the country and your bottle is discovered there then you may face other problems which could include deportation and a criminal record in that country. As such it could affect your ability to getaway in the future. Remember that simply because you do not get into serious trouble at property you will not have trouble in other locations. In some countries possession of alcohol can lead to prison time.
So, to summarize, yes you can get into trouble not just for possession of alcohol but for attempting to "smuggle" it. These days smuggling one thing can lead to problems in other areas. Who knows, you may end up on a "no fly" list.

Gee, I suppose that is such a clever way to disguise alcohol that the baggage inspectors have never heard of that trick.
Why would anyone carry a full bottle of water in checked luggage? It makes no logical sense to me, and won't to the inspectors either.
It is perfectly legal to carry alcoholic beverages in checked luggage, as long as it is less than 140 proof, so they won't be bothered by seeing a bottle of vodka. I do not know if they can or do check the ages of the passenger whose name is on the airline's luggage tag. If they do - you're busted. If they don't - no problems.
Just carry the bottle. Trying to hide it or disguise it simply makes it look suspicious.

Yes they will confiscate it all liquids are checked even though you check the baggage thinking its going under the plane those bags on the other side of the airport wall go though x rays and when liquids or bottles show up in the xray it beeps and the guy at the end of the xray pulls the bag to the side and checks and cameras are pointing at them they have to inspect it even if it looks like water they open the bottle and smell it and put it back if its ok but on your baggage tag it has your ticket# so they look up in the itenerary the # and flight # and next to that number shows your name and age thats why when you book tickets they ask for age of all the people flying and in order for you to check in and board your flight and get your ticket you need to show proof of your name or picture ID so they got you once the plane starts boarding they go on board the flight with the itnerary and look for your seat and pull you off the plane for questioning.

I would leave it in the real bottle. That way it will be better if you are found and trying to explain why you are smuggling it.
Be aware that if you are travelling internationally some countries prohibit minors from carrying alcohol at all, also be aware that you may need to pay an import duty if the volume is over the countries set amount.
If you are carrying it as a gift for example it should be ok in most countries.
Why do you need it?