It's a mans purse. An wallet type item, usually leather that is carried on or around the shoulder, know on occasion by "a European shoulder bag." Not to be confused with the fanny pack (made popular in the 1980's,which is worn around the waist). (Fanny packs are sometimes refured to as "fag bag's).
The differentionating factor between these "kissing cousins" is that the "fag bag" (To the layman)or "fanny pack" is:
A. Worn around the waist.
B. Usually worn by older bodybuilders or avid homosexuals.
The Merse or "man purse" is worn by anyone with bi-curosity in addition to flamboyant European heterosexuals, and finally men who are demasculinized by their wife.
Robert see's Fabian with a new kind of wallet, its almost like a wallet with a long shoulder strap, but its not a fanny pack, its a Merse, a mans purse. Robert is happy his boyfriend has a new wallet but isn't sure who gave it to him, Robert scream's " Nice fag bag", Fabian replies, its a Merse, a European shoulder bag you ignorant fool!