Happy Birthday to You
"Happy Birthday to You" was an Earth song that was typically sung at birthday parties.

In a coma he experienced after being attacked by a Lethean, Julian Bashir was treated to a performance of the song by a representation of Elim Garak (the form taken by the Lethean, Altovar) and a dabo girl in 2371. ()

In 2378, Seven of Nine gave Harry Kim an isolinear chip that would give him three minutes of comm time, admonishing him to "try to stay in tune" when singing happy birthday to his mother. ()

Lyrics
Happy birthday to you, 
happy birthday to you
Happy birthday dear (insert name here - in this case "Julian")
Happy birthday to you.

External link 
 

de:Happy Birthday to You
Earth musical compositions