Empty shell is an expression used for when you go for a shit and nothing comes out. Relates to turtles head, a turd that bobs in and out of your arse but in the case of a false alarm shit the shell is empty.
I thought I needed a shit but went for an empty shell instead.
To get all your cum sucked out and u cant bust a load
Damn my girl just gave me a empty shell and ir fell so fucking goood