I completely agree with everything thats been said so far. I just wanted to add that I have three burms and when they're small they're great but take him to a breeder/dealer and show him the big ones. Or let him get bitten by a juvenile so he can see that the adults could do alot of damage. He may think he'll breed rabbits for it and not waste money by just using minimal decorations but ask him what it would be like for him if his house had only food, water, and a bed. Thats the equivalent of that to a snake. As for the rabbits, does he realize a hutch, food (hay, fresh vegetables year round, fruit, etc.), a hide box, bedding, food dishes, water bottles, the cost of a rabbit itself, and any other costs he may run into will cost more than feeding the snake for a year on frozen or bought food? Also if you live in a climate that has harsh winters they will have to be housed indoors so their water doesn't freeze and they don't suffer (so add an indoor cage to the cost) At sixteen he should concentrate on a driver's license and school, not a snake that could make every neighborhood dog disappear. I am only 20 years old but I can honestly say that until I met my fiance and started our family I had no idea what "caring" for another needy being was like. A big snake is like a child and needs lots of care, attention, proper housing, feeding, and "clothing" (basically my description of an adequate tank setup). At sixteen I'm sure he's not ready for that and most teenagers feel that animals are more disposable than children. I can honestly say that my burmese (although still very small) are like children, they whine (hiss) when they aren't happy and don't always want to do what I want them to. They can also inflict alot more damage on your friend than his other current "pets". Please do the reptile community a favor and warn his parents what he's getting into. That snake will be an almost lifetime commitment for him and if he doesn't care for it, it will either die or be let go and prey on the neighborhood pets giving further fire to the legislators who are pushing for harsher laws on reptile keeping. Good luck but please do whatever it takes to prevent this (and maybe even do something to get better care for the snakes he already has.)
Link
-----
3.6 ball pythons
1.2 king snakes (1 chocolate, 2 albino)
1.0 columbian red tail boa
1.1 pueblan milksnakes
2.2 african house snakes
2.2 striped albino applegate gophers
1.0 watersnake
1.2 burmese pythons (1 albino, 2 hets)
2.1 pygmy rattlesnakes
1.1 dumeril's boas
3.3 corns (miami, okatee, snow, caramel, 2 creamsicle)
1.1 jungle corns