Since Clark wasn’t technically human there were many things that he didn’t do. One of those things were he didn’t age as usual and the other was that he didn’t celebrate his birthday. The reason for that was because it wasn’t his actual birthday, it was just the day his adoptive parents found him. But of course you being you, just couldn’t let that slide.

So it’s February 29, which only happens every 4 years so you had to take the opportunity, and Clark walks into your shared apartment from work

“Surprise!!” you yelled excitedly and he was obviously surprised, he didn’t even notice it was the 29th

“Oh thanks hun!” he said as he looked down at the cake that had his Superman logo, which was easy to get from the local bakery, and candles in an infinity shape since you didn’t know his age