Dad made me this outfit and it brings me special birthday luck every year.
|—Steven, In "So Many Birthdays"|
The outfit consists of a red King's cape entirely lined in thick white fur, and a red crown shaped like a heart with a white fluffy rim, a small purple and yellow heart in the center, and a little white candle on top.
- Garnet took a liking to the outfit, opting to wear it long after the birthday celebrations were over, as it made her feel important.
- One's "birthday suit" is a euphemism for having no clothes on as humans are all born naked.
- The crown of the birthday suit appears in the game Attack the Light, where it is called a Lucky Crown, and increases the luck of the chosen gem for the next five turns.
- In the promo art for StevenBomb 4, Steven appears to be wearing it.
- In "Steven's Birthday", Steven is shown to be wearing his birthday suit even as an infant for his first birthday.