Get that creative vibe going... you could design the costume for Roz to wear! After all, if she was willing to run around singing the national anthem in a public arena, surely this child's play?
I like the idea of a giant kangaroo...
Or what about Lleyton Hewitt? A blonde wig, tennis attire and all you have to do is run around yelling 'C'MON!!!' at the top of your voice

Ned Kelly? Wear a tin on your head with a slit cut in it. Dress up as a bushranger
A jar of Vegemite? A meat pie?

Will keep thinking!