Leftwing Idiot often goes for a run on a Sunday (Sunday Run-day he calls it) and before heading out this morning he was doing some warm up exercises at the castle.

He did some stretches and bends, and I barely noticed. But when he swung one leg repeatedly from side to side I burst out laughing.

I couldn’t explain to him what I found so funny but each time I saw his leg start to swing through the air I exploded into over-excited giggles.

This isn’t the first time I’ve found ordinary things inexplicably hilarious – sand, penguins, rolling-r’s, sawdust and cardboard envelopes have all left me laughing so hard I’ve struggled for breath.

I love it when laughter catches me by surprise.