Okely Dokely is the signature catchphrase of Ned Flanders, the cheerful neighbour in The Simpsons, in use since the show began in 1989. Adding Batman turns the familiar phrase into a mashup joke, pairing Flanders polite agreement with the famously serious Dark Knight. Short mashup clips like this spread on soundboards and in meme edits, where a recognisable catchphrase gets an unexpected name dropped at the end. The contrast keeps it reusable as a reaction sound long after the original context.