A fork of Rural Dictionary
Brown tint of fecal matter found on the tip of your finger after itching or playing with your anus. This is most commonly observed and then sniffed.
After a short jog, Jimmy reached down his sweats and scratched his anus. When he pulled his hand back up, he had a rusty finger, then sniffed it.
The art of fingering your butthole and then using your rusty finger to brush someones teeth. - Jim Williams
My wife loves my rusty finger brush. The rustier the better.
Like a rusty trombone, but somewhat straighter. Performing anilingus on your woman whilst diddling her vaginal canal. Classy move, and lets her know hepatitis ain't no thing.
Although I enjoyed that Rusty Finger Puppet last night, you might want to get a blood test.