Script to automatically change format of date in Acrobat

I know that Adobe has something built in where if you enter the wrong date format it will prompt you to enter it correctly. I am looking for a script that just automatically changes date to correct format. So if a user enters the year "15" when they tab or change fields it automatically changes that field to "2015." I know there's a way to do it I just can't remember the script for this.

Thanks in advance for your help!