Poptropica has recently added a new tool for your enjoyment: the Character Costumizer. With the Character Costumizer you can copy the clothes some other character you meet is wearing on. Now since guessing how to use it may become a bit complicated, here you’ve got some screenshots and tips:
Click on the green T-shirt icon in the upper right side of the screen -a Costumizer bubble speech appears when rolling your mouse over.
Next click on the character you want to copy all or some of the clothes he/she is wearing.
Choose the things you want to wear by clicking on them. Note that not all the items are wearable. Accept.