I don't want to be a third wheel.
我不想当电灯泡。
be a third wheel直译过来就是：“做第三个轮子”，自行车上装第三个轮子表示累赘，引申到男女约会时表示：“多余的第三者，当电灯泡”。因此，当美国人说"I don't want to be a third wheel."时，他/她要表达的意思就是:"I don't want to be an unwanted third party on a date."、"I don't want to disturb you two."、"I don't want to be the needless one."。
情景对白：
Terry: I'm going out with Iris tonight. Why not come and have dinner with us?
泰瑞：我晚上要和艾蕊丝约会，和我们一起吃晚饭吧！
Benjamin: You two go on ahead. I don't want to be a third wheel.
本杰明：你们两个去好了，我不想当电灯泡。
搭配句积累：
①It's your private affair and I don't want to interfere.
这是你的私事，我可不想介入。
②You two haven't seen each other for so long.
你们俩这么久没见面了。
③You must have a lot to confide to her.
你一定有很多话要对她说。
④Let's ask her out to dinner tonight.
请她和我们一起吃饭。
单词：
1. wheel n. 车轮
The car wheels spun and slipped on some oil on the road.
路面上有些油，汽车车轮经过时直打滑。
The wheel of history rolls on.
历史的车轮滚滚向前。
2. interfere vi. 涉入
I wish everyone would stop interfering and just leave me alone.
我希望大家都别再来干涉我，让我一个人静一静。
The UN cannot interfere in the internal affairs of any country.
联合国不能干涉任何国家的内政。
3. confide vi. 吐露
I knew she had some fundamental problems in her marriage because she had confided in me a year earlier.
我知道她的婚姻存在一些根本性的问题，早在一年前她就向我倾诉过。
He confided to me that he felt like he was being punished.
他向我诉说他觉得自己像是在受罚。
