This is the 8209th most frequent Japanese word.
差し込ん
"差し込ん" is the conjunctive form of "差し込む" and means "to insert" or "to plug in."
Used to describe light shining or entering a space.
暗闇の中に光が差し込んでいる。
Light is shining into the darkness.
Used to describe inserting an object into another object.
机の引き出しに鍵を差し込んだ。
I inserted the key into the desk drawer.
Used metaphorically to describe interrupting by inserting commentary into a conversation.