But what if the whole thing goes belly under?

The speaker, who is a flight attendant, was talking to her son about possibly taking a voluntary leave of absence in light of covid-19, but fearful about the financial status of her airline company that she works for.  This is a nice congruent conflation of “going under” and “going belly up”, both referring to a business that goes bankrupt or cleases to exist.  This is a directional (“under” vs. “up”) mixup, common in the malaphor world.  A big thanks to Jody Compton for uttering this one, recognizing it as a bona fide malaphor, and sending it in.

It will probably go belly under

The context of this malaphor was in reference to a newly opened restaurant that probably will not survive.   This is a congruent conflation of “going belly up” and “going under”, both meaning business failure.  Again, direction seems to be the hang up in this one (and many other previously posted ones), and of course that both phrases have the same meaning.  A big thank you to Jody Compton for serving this one up!