This document discusses debugging and profiling Ruby applications using a custom "WTF" tool. It describes: 1. Adding a WTF? method to print debug information and take optional formatting parameters like :pp, :yaml, etc. 2. Tracking method call times by wrapping methods to time them and collect stats. 3. Outputting collected profiling data on method calls and SQL queries run. 4. Packaging the debugging and profiling functionality into a WTF gem for easy use in other projects. The WTF tool allows printing debug information, timing method calls to surface performance bottlenecks, and tracking SQL queries run to debug application queries. The document outlines building this tool into a reusable Ruby