Forget me not

I don't know about this elephants never forgetting idea. My best friend is an elephant and he's always late if we've arranged to meet up, keeps saying, "sorry I forgot it was today." He's even got a bit of string with a knot in it but he can't remember if it's his bit of string, the knot is his which makes me think it's his bit of string. He keeps all his receipts but doesn't have one for string although he does have a receipt for a length of rope. I suggested that if he bought it from a very tall person then to them it might be string!! Trouble is, he can't remember where the shop is so we're still none the wiser. He was on Mastermind once but passed on all his questions.