Everybody else is waiting in line, so don't cut in front of other people.
People are standing in line, so you shouldn't cut in the middle of the line-up.
この場合、次のような言い方ができます。
ーEverybody else is waiting in line, so don't cut in front of other people.
「他の人はみんな並んで待ってるんだから、横入りしないで」
to wait in like で「並んで待つ」
to cut in front of other people で「他の人たちの前に割り込む」
ーPeople are standing in line, so you shouldn't cut in the middle of the line-up.
「みんな列に並んでいるんだから、列の真ん中に割り込まないで」
to stand in line で「列に並ぶ」
to cut in the middle of the line-up で「列の真ん中に割り込む」
ご参考まで！
カナダ 
