Fred Willard was arrested for lewd conduct last night in Hollywood when police allegedly caught him with his pants down in an adult movie theater ... TMZ has learned. According to law enforcement sources, LAPD undercover vice officers went into the Tiki Theater in Hollywood and found the 78-year-old "Anchorman" star watching last night's feature ... with his penis exposed and in his hand. We're told Willard was arrested around 8:45PM and booked for lewd conduct. It was a quick release -- we're told he was out of police custody a short while later. As for which movie Fred was...