Your profile says you are 18 years of age and your spelling suggests you are even younger.
Nevertheless, if you are responsible for a 12 year old and you'd like to do something fun together, there are numerous things the two of you can do.
Many cities have free admission to local museums and parks on a certain day of the month; you might see if such a policy exists in your area. (In my area, it is the first Wednesday of each month).
If you have roller blades or bicycles, find a new area to explore or visit your local skate park, if there is one.
Look in the paper for coupons for spa services and go get manicures. New shops often advertise two-for-one deals.
Like to bake or do crafts? Check out your local craft store for one-time classes. In most cases, these are free except for a small materials fee.
Check your local newspaper's activities calendar (or your public library) for a list of upcoming events. Many will be free or very low cost, only requiring a little pre-planning on your part and some available free time.
Use the resources available to you and don't be afraid to think outside the box.
