Rather coincidentally, Spoons also drew that! As in, the play on the WW2 dam busters.
I say its coincidental because I’m researching Spoons at the moment.
I’m a bit critical of it. I’m not fond of the immobile dam headcanon, and I prefer how some like Shadysmarty and Fiercedeitylynx depicted fluffy pregnancy, where the dams were still mobile to some degree.
I also asked Carp about it, and he clarified that mostly did this picture as a one-off.