For you and the rest of the peanut gallery, the joke here is honestly…. just kind of something you had to have lived through to really get?
So you may be aware that many Jews (in particular, religious Jews, but some secular Jews also) keep the dietary laws known as kashrut. The really, really basic meaning of this is that we only eat meat from certain animals that has been slaughtered in a certain way, and we separate meat and dairy. How people observe this in practice varies a lot. If you follow the strict traditional rules, you have separate dishes, cookware, and ideally appliances for meat and dairy. However, there is a whole continuum of practices that are more lenient.
In any event, for eight days a year, during the holiday of Pesach (Passover), those who keep kosher year-round (and even some who don’t) observe unique kashrut rules that involve removing all of the chametz (leavened grain products) from the household and one’s diet. If one holds by traditional observance, ridding one’s life of chametz in preparation for Pesach is a BIG deal, and includes a truly insane amount of cleaning and then the covering of surfaces that cannot be kashered.
It’s such an intensive process that once you’ve lived through it, it only makes sense to make jokes about it. Covering items that do not have and couldn’t even have food on them (see: the toilet paper) is hilariously over the top, but a good tension relief when you’re on your tenth hour of scrubbing your entire kitchen with a toothbrush to ensure that literally no cookie crumb has escaped.
