(TMZ) Kevin Clash, the longtime voice of Elmo, has been sued by a man who claims ... when he was a minor, Clash lured him to engage in lurid, crystal meth sex parties.

Sheldon Stephens says he was 16 when he met Clash at a social networking function for actors.  Soon after, Stephens says the two began a sexual relationship that escalated over a period of years.  

Stephens claims he was taken to Clash's New York lair by chauffeured limo.  While there, he alleges Clash smoked crystal meth during their sexual escapades.  He says Clash also gave him poppers to intensify the experience.

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