September 1958. "Rosalind Russell in costume from the film Auntie Mame posed with author Patrick Dennis (E.E. Tanner III)." Photo by Douglas Jones for the Look magazine assignment "The Man Behind Auntie Mame."
According to Uncle Mame, The life of Patrick Dennis, Edward Everett (Pat) Tanner III (real name) wore specially tailored, possibly self invented, similarly constructed dress shirts that buttoned at the crotch to be used doubly as underpants. Thus he kept his shirts tight, slim and fitted while preventing them from billowing. Having worked for years to get an athletic V shape developed I always thought this was a good idea for showing it off in dress clothing