You have to pick:

Might not be so bad having a child-like sense of wonder and innocence and stuff. Kind of sucks to be stuck with an adult body though, unless perhaps appearance is part of the "physical capabilities" of a 6-year old.

"lutefisk" or "lye fish" is a salty fish. I'm not sure how it tastes. but I'd rather have to eat that once than forever have the physical and mental capacities of a 6 year old.

I had to look it up:
Lutefisk is a traditional dish of the Nordic countries and parts of the Midwest United States. It is made from aged stockfish and lye. It is gelatinous in texture, and has an extremely strong, pungent odor. Its name literally means "lye fish."