A thin, usually dark and greasy mustache just above the top lip, resembling that of a stereotypical Mexican person.
Usually those with a true "creeper stash" also carry a baseball bat while wearing Bermuda or Mormon shorts, and pop out of expectable locations ready to beat someone up.
The character of "Martin" played by Danny R. McBride in the 2007 movie "The Heartbreak Kid" is a perfect example of a creeper stash.
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