Decorate your T-shirt to look like a high school athletic jersey. Use iron-on fabric or markers and fabric paint to place the last two numbers of your class graduation year on the front and back of a plain T-shirt. Above the year, place your last name, full name or your nickname. You can also put some other term of endearment, such as "class clown" or "popular girl."
You can also decorate your shirt with a class yearbook theme. Print iron-on pictures from your school yearbook and attach them to a plain T-shirt. Write phrases in fabric paint describing the pictures. You can put your class superlative, your school motto or some other pertinent statement on the shirt as well.
Make a fun and informative T-shirt covered with interesting facts about the school. Use fabric paint to write facts such as how many of the school football players have gone on to play professionally or the names of famous figures that graduated from or attended the school. You can also write more personal information related to the school, such as how many boyfriends/girlfriends you had during your time at the school.
If you simply want to show support for your school's team during homecoming, you can decorate your shirt with team boosting phrases. Also, you can gather several friends and get them to wear T-shirts adorned with large letters that spell out the name of the team or a short cheer, such as "Go Team."