You kept your Social Security card and you pasted stamps on it that proved that you paid it.

你取得社会保障卡,并将邮票贴在上面,以此来证明你已支付过钱。

耶鲁公开课 - 金融市场课程节选

You had to make--or your employer can do it for you-- they take the money to the post office and the post office would give you stamps.

你自己或者你的老板可以帮你-,将钱交到邮局,然后邮局把邮票给你。

耶鲁公开课 - 金融市场课程节选