When you give your partner a blumpkin (which is a blowjob whilst he is taking a dump) and remove it from the toilet to freeze it. Once it is frozen you then use it as a dildo and gradually let the poo melt in your anus so you can proceed to poop out his shit
When you are so incredibly desperate to defecate that your anal cavity begins to fill with a hot sensation as if your faeces have liquified in your anus
I'm in need for a melting john like or else I'll bust