Meaning of よこやり in Japanese

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Definition of よこやり

よこやり(yokoyari) 【横槍】

(n) interruption; interference; butting in
私の計画に横やりを入れないでください。
Please don't interfere with my plan.

よこやりをいれる(yokoyariwoireru) 【横槍を入れる ·横やりを入れる】

(exp, v1) to interrupt; to butt in
ふたりでまじめな話をしているんだから、君、無責任な横槍を入れないでほしいんだけど。
Hey, we're trying to have a serious discussion here so I'd appreciate it if you wouldn't butt in so irresponsibly.