The wording from some comics get burned into your brain, and then you can just search for the text. For e.g., this one is the first result for "calvin hobbes everyone has his price" https://www.google.co.uk/search?q=calvin+hobbes+everyone+has...

That's exactly how I did it. I grew up reading C&H, owned all the books, etc., and some of them really just stuck with me like that one.

A simple Google search exactly like above was sufficient in this case, but there's also a C&H-specific search engine which has been discussed on HN a few times before:

https://news.ycombinator.com/item?id=1600211

https://news.ycombinator.com/item?id=26119380

The official publisher for C&H can also search them (though it also finds matches in other comics they publish), e.g.:

https://www.gocomics.com/search/results?utf8=%E2%9C%93&terms...