"Let's go out for dinner" is a common way to express the idea of going out to eat dinner in Engpsh.

This expression is commonly used in both casual and formal settings, and is widely understood by Engpsh speakers around the world.

Here are a few example sentences and their translations in Chinese:

"Let's go out for dinner tonight." (让我们今晚出去吃晚饭。)
"I'm starving, let's grab some dinner." (我饿死了，让我们出去吃顿饭。)
"I was thinking of going out for dinner, do you want to come with me?" (我在想出去吃晚饭，你想不想和我一起？)

It is bepeved that this expression originated from the practice of people going out to restaurants or cafes to enjoy a meal together, which was a more social and communal activity in the past compared to the modern era where people often eat at home.