The first one is an oldie but goodie. The theme is cartoon characters such as Scooby Doo.
The second one is the ever popular Super Heros. This theme is as popular with younger children as it is with the teens.
The third one is apparel related. Go figure. As in Ed Hardy tees, cut by the famous Adam Saaks.
My friend Jeannette from http://www.jatyourservice.blogspot.com/ is working on a party for one of her VIP client's birthday. She made the awesome design above. I can't wait to see the final outcome. Feel free to check out her blog by clicking the link above.
So there you have it from the teens {male} perspective. If you want to know what is popular to a young person than ask them. Their response may just surprise you {in a good way}.