The “daingert Madelyn” in the last panel is from a CAPTCHA challenge. In case you’re not aware, CAPTCHAs used to present squiggly pseudo-words like that for you to decipher. I suppose they still might, but they used to, too.

And the joke is, well, it was always funny when the two words somehow made sense

Edit: And to totally kill the joke, “daingert” kinda looks/sounds like “dangit” in a southern(?) accent if you squint enough