Is Christina Aguilera saying wonderful things about Blake Shelton because they're super tight . . . or because she's promoting their new duet "Just A Fool"?  Yeah, probably both.

She told Chelsea Handler, quote, "I adore Blake.  All the guys on 'The Voice' and I are close but Blake in particular.  We used to have a seat next to each other, we banter a lot, we make jokes, we make fun of the other guys.

"He's just a good time, he's a good country boy.  We have a song called 'Just A Fool' on the record and it's my first approach at trying a little country."  (--Christina's new album "Lotus" drops November 13th.)