as fat as a pig 和猪一样胖；胖得像猪

【例句】
If I don't stop eating like this, I'll be fat as a pig.
如果我再不停地这样吃，我将和猪一样胖。

Never call someone as fat as a pig; that is impolite.
不说人家像猪那样胖，那是不礼貌。