Where can I bring a birthday cake?

I made mistake of bring one out today for my friends and told staff it was a surprise but they told me it isn't allowed. Idky I assumed it'd be the norm like in the usa. Now I had to bring it back but it ruined surprise. I see on Google it isn't allowed in most Japanese restaurants and I'm not allowed to have people in my hotel. It's also too cold outside. Where can I bring a birthday cake tomorrow?