Inglorious basterds - I don't get something.

[ThatllDoPig]

Watched this and thought it was very good, very tense. Wish some of it was true. However, I need someone to explain to me, the bit in the tavern when the english spy gives himself away by something he says about 'three glasses'. Later on the actress explains it to Brad but I still don't get it! What is it about this that is enough to make the gestapo scumbag realise he's not dealing with a german?

I think it's that German people count to 3 using there thumb first iykwim? Whereas we would use our index finger.

*their

Ah! Thanks heaps!

How strange-I don´t think I count like an English person!

I think if I was holding up three fingers I would hold up index middle & ring.

But count with my thumb first.

Diddl, thats it. If a german holds up 3 fingers to indicate 3 beers theyll hold up their thumb and first two fingers. An english person holds up three fingers.
With counting i think we would all start with thumb.

Actually, with my left hand I would hold up index, middle & ring fingers, with my left I´d hold up little, ring& middle.

Guess I´m odd!

And if I count with my left hand I start with my thumb, with my right I start with my little finger.

Guess I´m very odd!!

Isn't some of it based on true events ? Blowing up the cinema, obviously not with Hitler there.