Noun
mud kicker (plural mud kickers)
Alternative form of mud-kicker
(slang) A racehorse.
(slang) Streetwalker; a prostitute who looks for customers in public places, especially one who works for a pimp.
(slang) An unskilled laborer; One who makes his living by outdoor manual labor.
(slang) A workboot designed for outdoor work, especially one that can be worn on muddy ground.
Source: en.wiktionary.orgmud-kicker