Just in the spirit of Google Research, here's a reference to the Indian riddle in an old movie, not that I'm cheating or anything, but I'm probably cheating (but the answer's not here, so don't worry! Not that I'm lying!):
"Eugenia Lampert/Regina (Audrey Hepburn) about to try out her own lie-detector test (kissing) on Peter Joshua, alias Carson Dyle, alias Alexander Dyle, alias Adam Caulfield, alias Brian Crookshank (Cary Grant) in CHARADE (1963):
- Eugenia: 'Alex, how can you tell if someone is lying?'
- Alexander: 'You can't.'
- Eugenia: 'There must be a way.'
- Alexander: 'No. There's an old riddle about two tribes of Indians. The Whitefeet always tell the truth and the Blackfeet always lie. So one day you meet an Indian. You say: Hey, Indian, what are you? A truthful Whitefoot or a lying Blackfoot? He says: I'm a truthful Whitefoot. So, which is he?'
- Eugenia: 'Why couldn't you just look at his feet?'
- Alexander: 'Because he's wearing moccasins.'
- Eugenia: 'Well, then, he's a truthful Whitefoot of course.'
- Alexander: 'Why not a lying Blackfoot?'
- Eugenia: 'Which one are you.'
- Alexander: 'A truthful Whitefoot.'
- Eugenia: 'Come in. Sit down.'
- Alexander: 'Why? You want to look at my feet?'
- Eugenia: 'Yes.'"
http://www.movies-quotes.com/FUNNY QUOTES/COMEDY 1960.html
