90s kid here. i dont get it.

The one person was born in 2000 and the other person complains about how young they are. It turns out that the complainer was born in 1999, and therefore is only a year older. Thus making the complaint a bit silly.

I like to think he was born on 12/31/99 to make it extra ridiculous.

As that aging adult who was born on 12/29/99, it is extra ridiculous because 90s kids laugh at you and 00s kids think you’re already a corpse.

Technically a 90s kid!