In The Innocents Abroad he states it means grasshopper soup.  This is
when he is comparing Lake Tahoe to Lake Como.

On Sat, 2011-10-01 at 22:20 -0400, [log in to unmask] wrote:
> I'm thinking Twain might not have appreciated having his named on a book 
> about Lake TAHOE, since he preferred (at least in the days when he lived in 
> that region) to call it Lake Bigler. His dissatisfaction with Tahoe rested 
> mainly with the fact that it was the Indian name, and he thought it sounded 
> terrible, whereas Bigler had the advantage of sounding "Christian" and/or 
> "English." It seems to me he also wrote somewhere -- maybe even in Roughing 
> It -- that despite claims that Tahoe meant "fallen leaf" in the Indian 
> tongue, it really meant something low and trivial, like maybe "stinkbug." Or 
> maybe I just imagined that detail.
> 
> -- Bob G.