Fump

How come when you think you're going to fart, but you shit, there's a name for that? But when you think your are going to shit, but only fart, what's that called?

It's called a fump according to Tom Segura and Christina Pazsitzky.

I was hoping for more, but it was a fump. In other words it was a fart that failed in it's mission to push out the shit, because as my mother used to say "the farts push the shit out".