First Hand Theoretical Question

[kurtcobain]

First hand of a 1 (or 2, I dont think it changes things) table sit n go. UTG goes all, folded to you in the BB w/ AA. While you think, UTG turns over his cards, showing you KK.

Do you call?

At what buy in does it swing from a call to a fold? (For example, doubling up on the first hand of a $5 sit n go is far less helpful than on the first hand of a $500 one.)