"Let's stare at each other, whoever laughs, loses."
"Let's have a staring contest, the first to smile loses."
"Let's stare at each other, whoever laughs, loses."
"let's stare at each other" 「にらめっこしましょ」
"whoever laughs" 「笑うと」
"loses" 「負け」
"if you laugh, you lose" も言えます。
"Let's have a staring contest, the first to smile loses."
"staring contest" 「にらめっこ」
"the first to smile" 「最初笑うのは」