不是吃素的

不是吃素的:

Literally means:

not a vegetarian

Actually means:

吃素 means only eating vegetables, but not fish, meat, etc, implying that one is so kind that he does not kill animals for food.

This phrase refers to a tough person who is not easily taken advantage of so people should not look down upon, or underestimate him.

吃素：只吃蔬菜之类的食物，而不吃鱼、肉等食物（暗示远离杀伤的事）。

不是吃素的，不简单，很厉害。含不要小看的意味。