There are times when getting dolled up to hit the bars in Center City requires way too much energy. You have to wear uncomfortable clothes and shoes, and your finest digs aren't really conducive to sub-zero temperatures. If only there was a come-as-you-are spot where you could just let it all hang out and have a few in the meantime!
Fiume, the answer to your what-should-I-wear prayers, is perched up above Ethiopian restaurant, Abyssinia. Don't bother looking for a sign -- there isn't one. The bar is a neighborhood joint where anarchists rub elbows with left-wing grad students, literally. Space is tight but it doesn't seem to bother anyone. And if they don't mind the closet-like quarters, you can bet no one cares if you're wearing dirty jeans and flannel shirt.
Thursday night is bluegrass night and the music, coupled with the bar's Citywide Special ($3 PBRs and a shot of whiskey) is likely to bring out the good ol' boy in any cityslicker.