lookout for fantods

Two of my favorite words of popular parlance turn out to be in Huck Finn: Fantods and Lookout. As in "I know this tie will give your girlfriend the howling fantods, but it's not really my lookout, man."

Howling seems to be DF. Wallace's contribution, but other than that they both occur pleasantly in Huck Finn.

One thing i don't get about the story is what they're dang plan in. Huck and Jim go south on the river, hoping to get to Ohio, is it ? But then they miss the turn-off and end up going deeper and deeper south. This is the second or so time i've read it and knew to be on the lookout for The Plan, but i just don't get it. Well i'm about done, maybe it'll become clear.