stand up“起立”中间加上somebody后变成美式俚语，stand sb up表示“失约，放鸽子，爽约”。

【例句】
He was in a foul mood because he had been stood up.
他因被放鸽子而心情不好。

We were to have had dinner together yesterday evening, but he stood me up.
我们昨晚本来要一起吃晚饭的，但他爽约了。