1. Think outside the box 另辟蹊径

To solve this tough problem, we're going to have to think outside the box.
要解决这个难题，我们必须另辟蹊径。

释义：

box：常规的条条框框，老套路

outside the box：常规的框框之外

2. Third wheel 累赘，电灯泡

You two go on ahead. I don't want to be a third wheel.
你们两个去好了，我不想当电灯泡。

释义：

third wheel：自行车的第三个轮胎，显然多余。