Birthday cake

A birthday cake is an item that appears in The Sims: House Party, The Sims 2, The Sims 3, and The Sims 4. It is used to celebrate a Sim's birthday and ages up Sims to the next life stage.

The Sims
As there is no aging in The Sims, the birthday cake is little more than buyable food from buy mode. Sims can be instructed to blow out the candles, in which all playable Sims on the lot (excluding visitors) will put on party hats, gather around the cake and celebrate, blowing through party horns and rattling noisemakers. The "birthday Sim" will then bend down and blow out the candles, and will take the first slice of cake. Once the first slice is taken, other Sims can go in and grab a slice for themselves. The party hats and costumes will be removed once the interaction is cancelled or is completed. After the initial celebration, Sims can still eat the leftover pieces of cake, but will not wear a party hat.

When first placed, the candles will burn for two Sim hours. During this time, Sims can have a birthday party with the cake. Once the candles burn out, Sims cannot hold parties but can still eat the cake. The cake will spoil like any other food if it is left out for too long.

While it can be placed on the ground, the candles cannot be blown out unless it's on a table.

The Sims 2
Birthday cakes can be bought from the Misc > Party section of Buy mode. They are used to age Sims (except young adults and elders) to the next life stage, but can only be used if the Sim is within 24 game hours of transitioning. The Sim will still age 1 day at 6 pm, regardless of when the candles were blown out. Babies and toddlers can be aged up if a teen, adult, or elder carries them to the cake.

The Sims 3
The Birthday Inferno Birthday Cake is an object in The Sims 3 and can be bought at the supermarket. It can also be found in the Entertainment > Parties category in Buy mode, if Buy mode is set to "Sort by Function". It is used to age up a Sim by one life stage. It can be used to age up any Sim on the lot, not just Sims in the household. There's a 2% chance it will catch fire when Sims blow the candles.

The Sims 4
In The Sims 4, cakes can no longer be simply purchased from buy mode like in previous games. Cakes must be baked manually by Sims.