I don't think I know anyone else who would wish their friend a Happy birthday by saying "Congratulations on the anniversary of the successful exiting of your mother's birth canal".
Actually I typically go with something like "Happy anniversary of the day you were violently expelled from between your mother's legs in a bloody screaming mess!"
Well, yes, you are the only one who would use that EXACT phrasing, you aren't the only one with strange verbal versions of the phrase 'Happy Birthday'
Weird...