group of naughty boys; gang of mischievous kids
Refers to a group of children, typically boys, who are playful, mischievous, or get into minor trouble together. Often has a nostalgic or affectionate tone.
The neighborhood gang of mischievous kids is playing in the park.
腕白 is an adjective meaning 'naughty' or 'mischievous' (usually for children). 腕白仲間 is the noun for a group of such children.
Compound of 腕白 (mischievous) and 仲間 (group, companion). The origin of 腕白 is uncertain, but it is a common word for describing naughty children.