diff --git a/README.md b/README.md
index 05e7c86..c637f06 100644
--- a/README.md
+++ b/README.md
@@ -13,4 +13,6 @@ Usage
 
 `curl -n -d u=http://example.com linkie/path` will make `http://linkie/path` 302 redirect to the provided url. use .netrc to store the auth username/password (inspired by ix.io)
 
+`curl -n -d u=http://example.com linkie/_`, if you provide an underscore as the path linkie will generate a four character path from a-zA-Z. if it has a collision five times in a row it'll return 500.. at that point i'd probably increase the length of the random ids in the function at the top of index.js to 5 or something, and also i should get off the internet because i've generated 52^4 short urls with this service and that's insane
+
 See test.py for more usage and test cases