Besides ketchup, their slippery surfaces also aid the dispensing of products such as mayonnaise, and may help, too, with things like hummus and soured cream that have a thicker consistency and which usually come in tubs.
Other days, I would buy a box of Crunchy Nut Cornflakes or a tube of Pringles: sour cream and onion flavour stackable snack chips, which were an exciting novelty at the time, having only arrived in the UK in 1991.
Peel off all the burnt carbonized exterior, chop up the nice soft pepper underneath, and then cook those in crema, which is basically a Honduran sour cream.
We're going to go in for some toppings, we're going to dice up a red onion, we're going to have some sour cream, we're going to grate some cheese over the top, we're going to gratinate the cheese.