slosh (n.) Look up slosh at Dictionary.com
1814, "slush, sludge," probably a blend of slush and slop in its Middle English sense of "muddy place."
slosh (v.) Look up slosh at Dictionary.com
"to splash about in mud or wet," 1844, from slosh (n.). Meaning "to pour carelessly" is recorded from 1875. Related: Sloshed; sloshing.