When you are reviewing a PR in which the author has used utilities/libraries that were written by you(which were very generalized and DRY but required for you to read the docs to clearly understand their usage). But instead of using it properly they modify it for their specific usage and made a freaking PR. 

I just can't wait to finish the review and slap their face with a printed copy of the FUCKING docs. 

Seriously, read the goddamn docs. And, if you do change the lib, please update the doc too.