This doesn't really identify what it is you're describing. How about:
```
# Raindrops isn't loaded in development because we run under thin, but Raindrops
# is only loaded when running under Unicorn. Therefore, we need the conditional
# to prevent an undefined constant error.
#
# This middleware adds a /_raindrops path that exposes stats. To see this in
# development, start the app like this:
#    bundle exec unicorn -l 3009
```