Bilko's group (Company B) switches the sign on their barracks with the sign on Company A's barracks. One of the names on Company B's sign is Cpt. Hiken. Nat Hiken was the creator of the original The Phil Silvers Show (1955), on which this movie is based.
In the movie, Bilko holds the rank of "Master Sergeant" and though Master Sergeants are addressed as "sergeant", the rank is abbreviated "MSG" not "SGT" as in the title. "SGT" is the abbreviation for a buck sergeant, 3 grades lower than Master Sergeant.