For starters, leave all the thoughts and ideas of what to secretly bring the hamster home, feed, water him frankly and as "quietly" to get behind him, in the hope that when your secret is revealed, parents will be allowed to leave the animal at home.
Most likely, such secrets will not help and your pet at risk on the street. Needless to say that the hamster was on the street, doomed to death. So if you are determined to get that animal, do it openly.
Best any doubt wins the openness and facts. About the first we have already dealt with: talk to parents about the possible purchase of the animal in advance, so for anybody its appearance in the house was an unpleasant "surprise".
To convince households will allow information about hamsterX. Read a book for the maintenance of these animals (such literature is now easy to find even in bookstores), talk to the sellers at the pet store, ask them about the main difficulties you might face the owner of the hamster. Finally, it is easy to find specialized sites about rodents, as well as to read advice from experienced breeders of these animals.
After such information training you will be able to confidently answer all the questions that might be raised by your parents. In the first place, most likely, will be interested in: how you can care for an animal?
Tell us what hamster and harmless animal, which is easy to take up and let require regular but simple care. Note the simplicity of this animal: you can feed it vegetables, herbs, and special food for rodents is also very affordable.
Convince parentsthat you are going to clean the home of pet (by the way, for keeping a hamster is better to use special aquarium than a cage from which he can easily escape). Note that to get the hell out of you every other day to prevent the spread of odor in the apartment.
An additional advantage may be the mention of a friend who already has a pet. Seriousness of intent is to confirm and in order to prepare in advance the place you plan to put the container with the animal. Select a part of the apartment in which on the one hand, the hamster will be protected from sun, draught and moisture, and with another – will not be a hindrance to your parents.