OK, we see he has just sneezed, and the force of it has left her hair blown back, and evidently left stuck in that shape. And what’s the joke? Is it just that?
I for a few moments entertained the idea that it was meant to be super-Eww and the stripe in her hair represented the discharge of his sneeze! But co-editor phsiiicidu kindly set me straight, that it’s just the standard Bride-of-Frankenstein stripe; and he provided this reference image:
Comics I Don't Understand 
Yes, that is indeed all that there is to this panel.
P.S. That whitewall hair stripe has been parodied in any number of films, cartoons, and comics; notably in Mel Brooks’ “Young Frankenstein”, with Madeline Kahn:
P.P.S. Back in elementary school, there was a boy in my class who had a very similar lock of white hair. Luckily for him, we were far too young to have seen trashy movies from the 1930s, and Young Frankenstein did not appear until we were in junior high.
P.P.P.S. My favorite “Gesundheit” is by Berkeley Breathed:
Ever wonder how her hair got like that? Now you know!
And, of course, Terry Pratchett’s parody, Daughter of DEATH, Susan Sto Halit . . .
https://static.wikia.nocookie.net/vsbattles/images/f/f4/SusanStoHelit.jpg/revision/latest?cb=20190528121502
@ Andréa – I think the “revision” data prevented WordPress from embedding the image:
I didn’t expect it to embed . . . but thanks for doin’ that!
“Gesundheit” is (or used to be) a standard trope in comics. You never saw the actual sneeze, just the aftermath, and another party said “gesundheit.”
A quick Google Image Search on “gesundheit comics” shows that quite a few show up here, too!
I know it’s about her hair, but I love his hair – very modern style. Love the line work, too.
Pastry chef and YouTube star Claire Saffitz (originally from St. Louis) has a prominent white streak in her hair. She used to hide it, but these days has come to feature it.
Tom Falco has a post on his blog featuring this cartoon plus other recent panels he has done — plus past examples where he has depicted “Frank” and his wife.
https://tomversation.com/2022/08/17/frank-and-his-wife/
And of course, Ms Pedant here to state – again – the the monster has no name and Frankenstein is the name of his creator.
I’d say Tom Falco stays fairly well on the right side of that often-seen mistake. He says “The Frankenstein Monster, who I call Frank, …” which does give the monster a name but not just calling him Frankenstein.
Yes, I saw that, but . . . I dunno. Still sits wrong with me. Just ‘one o’ those things’, but I’ll give ‘im points for that.
And here’s Super-Fun-Pak Comix trying to slip one by in a double reverse play!
From my InBox today . . .
And it didn’t stop there!
I wonder whether he pronounces it “Frahnkensteen“…