What word or phrase does your mother always say?
1530s, "waste discharged from the body," from Latin excrementum, from stem of excretus, past participle of excernere "to sift out, discharge," from ex- "out" (see ex-) + cernere "sift, separate" (see crisis). Originally any bodily secretion, especially from the bowels; exclusive sense of "feces" is since mid-18c.
excrement ex·cre·ment (ěk'skrə-mənt)
Waste matter or any excretion cast out of the body, especially feces.