......Its not cricket and its less to do with holding the slipper wrong, more to do with it is inherently unstable along that axis, its a mathematical solution to quote the reference above.....

"Why does it do this? The reason is because the principal axes with the greatest and smallest moments of inertia are stable. That is, if you spin around these axes, the object will continue to spin in more or less the same direction, even if you didn't spin it in exactly the right way. However, the principal axis with the middle moment of inertia is unstable. If you didn't spin it in exactly the right way, or if air friction pushes the box just a little bit, it will start spinning in all sorts of weird directions.

It's sort of like carrying a handbag. It's easy to hang it over your arm, because that is a stable position. But it's difficult to balance it on your head because that is an unstable position. Stability and instability are important concepts if you want to think like a physicist.

As for why two of the principal axes are stable and the other is not, that is a difficult question with a very mathematical answer. It has to do with three equations called Euler's Equations."

(the equations are inserted here in an image in the reference)

"They are a mathematical consequence of Newton's Laws. I know many of you are looking at that and thinking, "Those equations look so ridiculously complicated!" In this case, you are absolutely right--these equations are ridiculously complicated, even after you learn about differential equations. But even if we don't solve the equations completely, we can still make qualitative predictions. If you have a cubical or spherical object, its rotation will remain constant. If you have a weirdly shaped object like your box, its rotation is stable around the principal axes of smallest and largest moments of inertia, but unstable around the third principal axis."