Birthday cake

The Birthday Inferno Birthday Cake is an object in The Sims 3 and can be bought at the supermarket, and can be found in the "Parties" Category of "Sort by Function" in Buy Mode. It is used to age up a Sim by one age category. It can be used on any Sim on the lot, not just Sims in the household. However, it can only be used once per Sim. Occasionally, it may catch fire.

This is incorrect that it works only once per Sim. My Girlfriend did it twice with her Sim "David". First, he was a toddler, then she gave him the cake. He became a kid. Then she gave him another cake about two minutes later, and he became a teenager. - vB-