"Gragra!"

I have been confused as to the titles which should be used for my servants. I was under the impression that "Daddy" was a title imparted upon whichever servant was the best at tossing me into the air and tickling my toesies. Under my false knowledge I thus began calling one particular GrandDaddyServant "Daddy" as I assumed this was a title I was able to bestow upon him. I was apparently incorrect, as I was told on various occasions. Now I know to call Daddy "Dada" or "Daddy" or "Dad" or, most often, "Da'y", and GrandDaddyServants are called "Gragra".

I am told this shirt says "ADORE MY GRANDPA". As that sentence has no acting noun, I am unsure what it is supposed to mean, and can only assume that my shirt is giving all who read it a command.