My cousin, the author Rachel Vail, has a family rule called "plums are not a one-bite food." At the home of another friend, there's a rule called "nothing, and no one, rides the cat." Chez moi, we have "yogurt is not a finger food." You can imagine the events that led to developing these rules.
Basically, the moment your baby can sit up, you find yourself saying the darndest things. Sometimes with a straight face.
Since art imitates life, one dad has made his odd kid remarks into paintings you can buy on etsy.
If you like this stuff, let me also recommend the short video series, "Conversations with my two year old" where a real dad and another grown man act out actual conversations between a parent and toddler. (the little pink barrette makes the whole thing).