My granddaughter Jasmine loves to sit on my knee when I'm in my computer chair. She particularly loves to play Happy Mrs. Chicken - who lays eggs at a click of a mouse with a loud - and rather rude - razz sound.

Little girls, even those like Jasmine who have graduated from diapers to 'big girls' knickers', do not have a sophisticated sense of humour - so every loud razz was accompanied by a fit of the giggles. Even I was infected and had to grin.

Then I froze - well, to be exact most of me froze - except my lap which was suffused by a spreading warm glow closely followed by a spreading feeling of extreme dampness ...

I shout to her Mom to deal with Jasmine whilst I survey the damage, get a shower and change. Bye-bye black jeans.

MEMO TO SELF : do not amuse novice wearers of big girls knickers, whilst they're sitting on your knee.