I read somewhere that "it's a 'Tarantinoism'".
Drexl Spivey: Grab a seat, boy. Grab yourself an egg roll. We got everything here from a diddle-eyed-Joe to a damned-if-I-know. True Romance
To me, it just means that they have everything you could possibly want to eat. In Reservoir Dogs, that's probably the same meaning: I'd bet everything I have (and you can think of) that I'm right.
As Drexl has a dead eye and portraits himself as an African-American, I've always wondered if it was a kind of play-on-word/reference to Cotton-Eyed Joe (because that song was sung by people in plantations).
'Damned-if-I-know' is a pretty standard expression, but I never found a good translation/reference of the 'diddle-eyed-Joe' part, so I have to go with my understanding of it, it probably has to be taken with a grain of salt... (or corrected by a native speaker.)
As Tarantino always adds many references to himself/others, it's quite difficult to know why he did use the expression again. He may have loved the 1972 movie...