Simplest solution yet.

>! Lay this on a plank of wood. John can pick it up the plank and marvel as Bob collects his beer.<br><br>![Nail and hammer][1] <br><br>If you want to get technical about straight lines, he could flip the nail the other way, and use a plank to jam the 'head' of the nail into the hammer shaft to form a straight angle, or simply use the hammer to bend the nail head to the desired angle before producing this solution.


  [1]: https://i.sstatic.net/riBfm.jpg