Dlabaj probably comes from the verb dlabat, to pick, chisel, gouge, peck. Dlabaj would be the adjectival participle form, e.g. [one who is] chiseling. Mrnustik may come from mrně or mrňous. If so, a possible translation would be "little kid." Note the ending sounds more Slovak than Czech given the fact that it has a "u" rather than a "ou" in the stem.
