This word can be used as a verb to indicate checking the validity of a suspect story. It is derived from the online urban legend reference site: www.snopes.com.
That sounds fake. You should snopes it.
Also
She told me a story about a friend of a sorority sister who had a huge pimple that eventually exploded hundreds of baby spiders on her face, but I snopesed it, and that story is just an urban legend.