If someone's behaviour or action is foolish, it is not sensible and shows a lack of good judgment.
It would be foolish to raise hopes unnecessarily.
期望过高是愚蠢的。
If you look or feel foolish, you look or feel so silly or ridiculous that people are likely to laugh at you.
I just stood there feeling foolish and watching him.
我就傻乎乎地站在那儿看着他。