What's the use of the cake in Chapter 2

[我吃烤全羊]

I paid 3 gold coins and got no response

[MarielaRF]

Maaaaaaybe there's something else to do to unlock something very cool...

[Zeke]

get it behind your walls and let your unemployed kids gather around it
its a birthday cake, let them have a party

(not sure if builders count but archers dont, so leave your recruits (2-3+) without jobs and the party will happen)

[Beravin]

When the party ends you can open the giant present next to it.

[Sopito]

I'm divided between the skateboard and the present