Send this card to your friend and wish a rocking Birthday bash. Rocking Birthday scraps, Rocking images for Birthday, Rocking Birthday comments, Rocking Birthday graphics for all kind Birthdays.. Rock music is a loosely defined genre of popular music that entered the mainstream in the mid 1950s. But it's still rocking us. Rock, reggae, rap and roll or jazz! It's just a way to wish your friend Happy Birthday.