Nibble off opposite corners and place one end in mug of boiling water. Suck the water up the Tim Tam, melting the chocolate and burning your fingers in the process. The first person to finish their Tim Tam wins.
Per Wikipedia: "Penguin biscuits are milk chocolate-covered biscuit bars filled with chocolate cream. They are produced by United Biscuits manufacturing division, McVitie's. The Tim Tam produced by Arnott's in Australia was based on the Penguin, and much debate has ensued over which is the superior biscuit."