You have to do it in person. Head to the bakery department of your local Costco, and look for the ordering station. Grab a "Special Cake Order Form," fill out the details, including your phone number, ...

In May, a tweet shed light on Costco's cake-ordering process, which some people called outdated. You can't call to order — you must write your order on a form and physically slip it into a box.

Rules can vary by location, but generally speaking, if you want a custom Costco cake, like adding a name or message for a special birthday ... There's an order form, a box—and a leap of faith.

The order form also offers decorating options ... You can absolutely order a birthday cake from Costco. Special-order options include balloon icing decorations and writing on the cake.