Cartoon conventions

Noel is reviewing a collection of Laurel and Hardy shorts this week. These comedies and their ilk were the models for many of the Warner Brothers cartoons I watched obsessively as a kid.

In "Tit for Tat," L & H have a feud with a neighboring business owner.  Each time they leave his grocery store after dealing him a reciprocal humiliation, they pick up marshmallows out of a display box near the door and pop them ostentatiously into their mouths.  At one point, the store owner picks up a canister that the close-up tells us is POWDERED ALUM and sprinkles it on the marshmallows.  As anyone who has ever seen "Long Haired Hare" could predict, the next time L & H eat the marshmallows (going back for seconds this time for good measure), their mouths pucker up such that they can't speak, and they have to spray seltzer in each other's mouths to recover.

Alum is one of those gag items that seemed to me in my youth to have no existence outside of cartoons.  It's used in pickling, Noel tells me after a quick look at Wikipedia, and as a hemorrhoid remedy, among many other household uses.  To me it occupies the same realm as the anvil (familiar in a bygone age of blacksmithery, but not exactly a common sight thereafter), "Those Endearing Young Charms," and yes, the seltzer bottle.

What props or plot devices populate the comedies or cartoons of your upbringing, without a chance of being glimpsed in real life?