Too stupid to live, but too beloved to die. Harry and Lloyd, the dim-witted stooges running on a fistful of neurons in 1994's Dumb and Dumber, are back. Even after two decades, returning costars Jeff Daniels and Jim Carrey found it easy to slip into that empty headspace again. ''From the minute we started filming, it was like we went back in time,'' says codirector Peter Farrelly. When the pair learn that Harry (Daniels) may have fathered a daughter, they set out to find her in hopes that she might donate a needed kidney. Of course, what he could really use is a brain transplant. ''It's very freeing to be that stupid, very Zen,'' says Daniels. ''I'd highly recommend it.''