You think you know a girl...

But you really dont.
That's the whole point, which might seem obvious to guys who have had an experience and ridiculous to those who didn't. But my case is that after having had a couple of experiences, still I couldn't get this thing into my mind. May be writing it somewhere would benifit me in avoiding a fall flat on nose the next time.
In short if I had a little younger brother, what I'd suggest him is... 'girls, particularly those who you think match your taste, will turn out to be extremely complex in their mind. So better close the shop, stay away and remain silent (best thing of all times). Eating lunch in your own cafeteria is far better than attending a lunch invitation given by girl(s). Don't even think about you trying to convince them for a lunch outside. It's only next to possible.'