Drop in whenever you come to see your parents.

你来看望父母时顺便来我这里坐坐。

　　动词词组drop in，顺便或偶然到访（某人或某地）。
　　例句：
　　She dropped in to see a great friend of hers.
　　她顺便去看看她的一个好朋友。
　　While waiting for the bus, he found himself in front of a small shop; he dropped in to buy some chewing gum.
　　等公共汽车的时候，他发现面前有个小店，就顺便进去买了些口香糖。