Question

One, because they're high. Two, because they're insulted by the steroetypical implication of Indians just hanging around waiting for a white man to give them directions.

Don't know if you still care about this question - but I just watched the dvd and it was answered in the commentary. Ari and Mouse had been discussing what their lives would be like (now) if the indians never welcomed Christopher Columbus. Lo and behold, they stumbled upon their very own "Christopher Columbus" and beat him up.