What is the deal with the Indians?

The thing with the Indians just makes me laugh every time I think of it - it's so surreal. There they sit, in front of Mr. Snavely's fireplace, and he walks in the door and doesn't even see them! He walks around the room shouting for someone to come, and never reacts until one of them speaks to him:

"How, Mr. Snavely!"
"How, Chief!"
"How!"
"And how!"

Then he just throws them out! By the way, what is the second thing he says as he's kicking them out? I got "Vamoose" and "Lam", but what's the one in between? It should be "Amscray", but it sounds more like "Ooscray", which would be something quite different!

Flat, drab passion meanders across the screen!