Thumblista — the under your thumb shopping list idea

During the work together (a team exercise — we call it 'speed redesigns' ;), we decided to focus on 1 aspect of design/usability of grocery list app. My choice was a thumb that could be the only thing(er) used while shopping. The other hand grabs groceries so we have only one thumb. Is this a fun idea? Rather usable :) Enjoy & Bon appetit :) I know that you can invent something even more fun!