Japanese by Example
Learning through examples in manga

Leaving a door unlocked with 〜っぱなし

ポケットモンスタースペシャル » Volume 5 » Page 92

Blue tries to sneak into Masaki’s cottage, but the door is locked.

ブルー:
()っぱなし…なわけないか。まあいいわ。」
"There's no way it'd be left unlocked. Well, that's fine."