(Short for "Texting While Pooping")
1. When your life gets too busy to respond to your text messages, you have to rely on the five to ten minutes on the toilet to text people back and you don't want to call anyone because they may hear you pooping.
2. A great excuse often used so you don't have to call someone at that particular moment.
(In a text conversation)
Sally: "Can I call u?"
John: "In a little bit. I'm TWP."
Sally: "Ur fucking gross."