COIS'TREL, noun [Old French coustillier, a soldier armed with a dagger, from coustel, a dagger.] a young lad or inferior groom, employed to take care of a knight's horses; hence, a mean, paltry fellow; knave; varlet. [Archaic.]
"Quick! Colicky kids cause coistrels kicks"
(Try again, Chris...)
"Quick! The coolant's not cool currently; can't captain that car. Call up a coistrel (with corresponding colt) so Carl can call upon Carl's concubine."