I mentioned this in the other file but, Marmite and ketchup. Classy, me.
Never thought I'd ever try the classic Peanut Butter and Jam.
I never 'got' this either, until I had one in the US and discovered I was Doing It Wrong.
For a classic PB&J, first you need to realise that the ratio isn't 1:1. You need a good, thick layer of PB and the 'jam' waving at it.
Second, they don't use jam, it's what they call "jelly" and is way thinnner and runnier than our jam. I ask for a jar of Smucker's jelly when people go on holiday; the closest I've found over here is the stuff that comes in squeezy bottles. Selfridges sell Smuckers, but they only do grape flavour which I've never had the courage to try (-: They also sell Jif peanut butter, which is the holy grail of PB&J peanut butter.