In stone skipping, one tosses a stone with a flattened surface across water (or other fluid) to try to get it to bounce as many times as possible. (There are also military applications, but let’s stick to the fun stuff.)
A few months ago, mechanical engineer Tadd Truscott and collagues wrote a quick study on the physics of water-skipping stones (and spheres) in Physics Today. Among other things, they examined possible angles of attack and how they affect the subsequent skipping. The series of images below comes from this article.
Bonus: This is far from Truscott’s first improbable study of splashing. For example, he has also studied splash damage in urination.