boys' play
/ˈbɔɪzpleɪ/Now rare
noun
Play or activity befitting a boy; (hence) something trivial or easy to accomplish; = child's play.
Origin
Mid 16th century; earliest use found in Thomas Elyot (c1490–1546), humanist and diplomat. From the genitive plural (or perhaps originally the genitive singular) of boy + play, probably after child's play.