More commonly used in areas inhabited by the H-E-B grocery store (Texas and northern Mexico), H-E-B Feet is a state in which someone who hasn't worn shoes for a while looks as though they've been walking through a particularly dirty H-E-B.
a: Damn, that boy's got some dirty ass feet!
b: Oh shit, he's got H-E-B Feet.
HEB is a large grocery store chain across Texas and Mexico. If you were to do some grocery shoppin' barefoot, HEB feet is what your feet would look like when you were done. Is used to describe dirty feet in any scenario, but the term is derived from the barefoot grocery shoppin' experience.
Girl: Ew, you got HEB feet.
Guy: Hell yeah! I run with dogs!