ISO Someone To Jump Out Of Cake

ISO someone to jump out of this cake for someone’s birthday. I already did 95% of the work by baking it but would like to add a little more surprise in. The cake is 5×7. Couple ground rules: Cake must not be ruined.

Ideally, you would jump out after the first stanza of “Happy Birthday To You!”

Pay is contingent on experience. DM serious inquiries only.