I don't know what it is, but the Sunday ones are like comedy Kryptonite. They just
repel laughter. Which reminds me of a story: when I was a kid, I had these little toy Scotty dogs with magnets glued to the bottom. The idea was that the magnets would either repel or attract each other depending which direction they were facing, so you could make the dogs "kiss" or "chase" each other. It was a neat toy.
HOLY CRAP, YOU CAN STILL GET THESE.
P.S. - Here's a "tweaked" version of the cartoon, meaning I was seriously
tweaked when I came up with it.