What does "didly ho" mean? It doesn't sound familiar. Is it a dialect?

Native speaker’s answer
Rebecca
"Hi diddly ho" isn't really any expression at all! It's a catchphrase used commonly by Ned Flanders from the Simpsons. Instead of simply saying "hi," he likes to add made-up words like "diddly ho" to it. This video is a reference to Ned's greeting. People don't say this in real life!