Reddit glossary
What is Cake day on Reddit?
Your cake day is the yearly anniversary of the day you made your Reddit account.
A small cake icon appears next to your username on that day. People often wish each other a happy cake day in the comments.
If you are promoting something
It is a small thing, but a cake icon on a long-running account is a quiet sign of history. Do not mention it to look more trustworthy. Let the account speak for itself.