One of the most rewarding aspects of parenthood is knowing that your love and hard work will provide a bright future for your child. Harboring parasitic botfly larvae is much the same. Nestled snuggly in the warm confines of your skin, it depends on your loving support (and tasty tissue) to enter the next phase of its lifecycle.
Botfly larvae enter the human body through mosquito bites (the adults actually lay their eggs on the unwitting delivery bug). Once inside you, they anchor themselves in place with hooks and raise a breathing tube up through the skin. Of course, you'll have to make sure you don't cover up the tube -- and certainly don't tug on it. Aside from killing your new pet, you could cause a serious infection.
Bear in mind that your new best friend is going to cause a certain amount of itching, as well as a shooting pain if it moves around too much. As such, try not to stress the little guy out. Avoid swimming or taking a bath, as these activities cause the larva to freak out over lack of oxygen. As your pet grows, a lump forms over the nesting site until the fully-grown larvae finally emerges painlessly. Think of it: The tiny larva has used your flesh to make itself a stronger body -- and eventually it will transform into a full-grown fly!
Other selections: If you're not up for such a commitment, you can always fallback on bed bugs -- which are becoming quite the fad again! You also might be interested in a chest full of lung flukes or a few screwworms if you happen to visit a country where they're still plentiful.