"What happened to you?" "The fucking splibs got me." "How'd you get away?" "Well, they trashed me (folded in half and wedged into a garbage barrel) and took off with my sister." "WOW, pretty lucky!" "Yeah, that's about the first decent thing the splibs ever did."
"Hey, Mr. McGivney was robbed yesterday with a gun!" "Was it a splib?" "Naw, all the nigger wanted was his wallet."
I did not perceive it as derogatory at the time, more a hip code-word among the jivers (those speaking jive-talk).