他天真得可笑。

He was ridiculously naive.

我觉得可笑。

I think it's ludicrous.

你觉得可笑，我却觉得可悲。

I think it's really absurd but I also think it's tragic.

十分可笑的理由

extremely ridiculous reason

说来可笑

funnily enough

真是可笑。

It's really ridiculous.

可笑之处在于...

there's absurdity in

可笑的是她竟然信以为真。

What's absurd is that in spite of everything she fell for it.

这有什么可笑！

what's so ridiculous about this!

可笑的事儿

funny thing

讲得太可笑了

be spoken very amusingly