Today is the day you’re mostly likely to be saying “HAPPY BIRTHDAY”
September 9 is the most common birthday day.  

Here are a few today: Adam Sandler, Michael Bublé and Colonel Sanders

Note:  Some sources say the most common birthday day is 9/16.  
Whichever day is right…You should celebrate all month anyway! ;0)

PS:  It’s also National Teddy Bear Day…now you know!