YOU SAID:

Haha, you're so fat you can't fit into a train

INTO JAPANESE

ハハ、あなたは電車に収まらないほど太っている

BACK INTO ENGLISH

Haha, you're fat enough to fit on the train

INTO JAPANESE

ハハ、あなたは電車に収まるほど太っています

BACK INTO ENGLISH

Haha, you're fat enough to fit on the train