"This looks pretty good"
The secret shirt in Strong Badia the free is of the Queen Bee from Fright of the Bumblebees, the first episode of Wallace & Gromit's Grand Adventures. To get the shirt, jump off of the ledge in the Snap Shak until Strong Bad lands upside down (you can't be wearing a costume for this to work). Now try to enter the door from the bottom. If all goes well, Strong Bad should now be wearing the shirt.