hi slinky kate. Seemingly mad as a hatter came about because of the substances used by hatters (years ago) when making the hats. They inhaled the fumes and ended up a bit gaga. That's the explanation I heard any way. Sorry if it's incorrect
......laughing is an aphrodisiac (release of endorphins and all that) I don't know about you but my socks come of before a bit of bedroom gymnastics so maybe that's it..... oh and it was mercury fumes that sent the hatters mad......