I don't get this joke about Hitler

Most likely, no one in the audience would have gotten the allusion, since the slang term was no longer au courant. I certainly wouldn’t have.

In line with the above, Hitler was notorious for his flatulence. He apparently had something like irritable bowel syndrome, aggravated by his vegetarian diet. After one meeting with some particularly important aristocrat and potential Party backer in the '20s or '30s, she leaned over to a servant and said sotto voce “Open a window, please. It stinks in here!”

I think I get it, this is actually like those old fashion bad words/line substitutes, like “Oh Sugar!” “Fiddlesticks” to replace Oh shit and fuck. “piece of cheese” seem to be a bad word substitute for the common insult of calling someone a “piece of shit”

Possibly the idea is that Swiss cheese is full of holes, and they’d like to see some gunmen put him in the same condition …?

“Who cut the cheese” referred to the fact that many kinds of cheese (like Limburger) are very stinky. Because of this the phrase was a euphemism for “Who farted?” Cheese wasn’t actually a slang term for crap.

Would you like a slice of Hitler on that sandwich?

I know I’m late for the party, but that was funny.

No thanks, it gives me gas.

Though in fact, Hitler became a tea kettle.

But only to non-aryan cheese.

I am NOT bragging, but I have an M.A. in folklore, and I actually collect slang from the past. (In the 1930s and 1940s, “Everything’s jake” meant "Everything’s just fine.) So you’re right: a piece of cheese was a fool, a jerk; but it was also a humorous euphemism for excrement.

You’ve got it, Winnipeg. In those days, “a piece of cheese” meant excrement. Today, “to slice of cut cheese” is a humorous euphemism for breaking wind. Fart.

What happened at Hitler’s last golf game!

He ended up in the bunker!

Al Gore was so boring, his secret service code name was Al Gore.