This discussion may contain spoilers!
Costume Items List!
1.Chain Boots - Click on the dresser in Strong Mad's room in the House of Strong.
2.Leopard Print Pants - Click on the couch in Strong Bad's basement.
3.Leopard Headband - Use the Microphone in front of the brick wall that's in between The Stick and Bubs'.
4.Sloshy Shirt - Use the Microphone in the laundry room in the basement.
It's pretty complete, tell me if I missed anything, also if anyone remembers how to get the head band, please say so.