Howie Mandel -- Thiiiiiiis Close to Porn

For a guy who hates to get dirty, it's pretty hard to believe Howie Mandel just moved his production company into an L.A. office building famous for housing the biggest PORN company on Earth!

But it's true!!! TMZ has learned Howie just took over some office space in the Vivid Entertainment building in L.A. ... right around the corner from Universal Studios.

Vivid honcho Steve Hirsch tells us he's very excited to hang with his new office neighbor -- and personally gave Howie a tour of the building last month.

Hirsch tells us his team is more than happy to do "whatever it takes" to make Howie feel comfortable at the XXX compound ... adding, "We even painted the walls and replaced the carpet."