Reading my comment back makes it sound more dick-ish than I intended, my bad. You just happened to mention a special interest of mine that I know a lot about.

I have my 03-FFL, and “Curio & Relic” is a classification that firearms can fall into, defined as firearms manufactured 50-years or more ago. Legally, by definition, you are still purchasing a firearm. You’ve just had more background checks to bypass some of the rules in most states about transfers, if the firearm you are buying qualifies as a “Curio & Relic”.

The “cake” is a literal cake, and the concept is printed pictures on sticks or straws that you put into the cake as you mention or explain the unconventional person. It’s just a “viral” online trend, a random fun thing friends do.