Elton John Sued by Security Guard ... Singer Tried to Grab My 'Todger'

Sir Elton John forced himself on a former security guard, grabbing the man's genitals on multiple occasions ... at least that's the claim in a lawsuit just filed against Elton.

Jeffrey Wenninger says 3 alleged incidents went down in 2014. In the suit, Wenninger says he and Elton were in a car together when Elton put his hands in Wenninger's pants. He says Elton attempted to grab his genitals and put his fingers between Wenninger's butt cheeks.

According to the suit, Elton then told him to "Get your todger out" and "say hello to Uncle Elton."

Wenninger says he attempted to verbally and physically resist, but it never deterred the singer.

Wenninger says another time, also in a car, Elton twisted his nipples and said ... "You gorgeous thing, you." Wenninger says there were several other incidents during his employment. He says he stopped working with Elton in September 2014.

He's suing for sexual harassment and battery. We've reached out to Elton's reps, but no response yet.