FYI:

I am a member of a Black Greek sorority {Alpha Kappa Alpha, Inc.}.
Black Greek letter fraternities and sororities {and the fraternities' little sister groups} are serious business. There are under graduate university and graduate chapters, and some people are very very active in these groups throughout their entire adult life.

The Greek letters that have "f*** them" after them respond to the Sigma's rival university Black Greek letter fraternities: Alpha Phi Alpha {also called "Alphas"}; Kappa Alpha Psi {called "Kappas"} and Omega Psi Phi {most often called "Q's" but also called "the men of Omega"}. *

The "Most gracious Sisters of Zeta" is a reference to Zeta Phi Beta, whose sorors {members of the sorority} are considered sisters to the Sigmas.

Each fraternity and sorority has its own colors, hand gesture, chants, calls, symbols, and steps. Step {steppin} is syncopated synchronized foot stomping to chants and/or {since at least the 1990s} recorded music. A sub-set of steppin is "the party walk" which is a processional steppin to recorded music and/or chanting.

* In addition to these Pan-Hellenic incorporated groups, there is at least one more fraternity called the Iotas.

I remember when I was in college there was also a spoof on the fraternities called I Felta Thi.