The Rehbinder effect

It reduces the strength of material due to reduction in surface energy

Why this thing is not in my physics book

Actually, that's pretty interesting. Thanks for sharing!

You learn about this in Manufacturing Engineering degrees. Has a particularly relevant application when you’re dealing with things like cutting fluids and lubricants. At least in my field.

At last I know it. Mug with a hole is something what I need.

Water absorbs body vibrations

Does this have some crazy acoustic reason for this? Does the water block the shock wave propogation through the material or something like that?

Don't try and punch someone under water or you might make a hole in them.

viscosity of water helps prevents fracturing in brittle materials caused by vibrations.