for example, i've no idea why my brain has retained since probably the late 90s, that advert for a yoghurt that was shaped like a UFO and had something in the middle of it. Occasionally I think about it. I don't know why.
Also occasionally for no reason appears: "MMMMMMMMmmmm, Danone"
Come to think of it they're mostly adverts from childhood. Looks like the ad. guys were playing the long game cos I certainly didn't buy anything when I was about 7.