Justin Timberlake has never been shy about his penchant for pot. In a recent interview, JT said that marijuana helps him to "stop thinking" and "some people are just better high."
Maybe Timberlake was thinking a few pre-show tokes in the green room would make him a better guest on tonight's Late Show? His bumbling, confused answers to David Letterman's most basic questions certainly support the whole "not thinking" thing. Not so sure about the "better" part, though.