Smoothskin

Smoothskin is a derogatory term that ghouls use to describe someone who is human, referring to the less ravaged outward appearance of humans compared to their own.

In Fallout 3, the player may ask Winthrop about the name upon entrance in Underworld, to which Winthrop will reply because the player's skin is so smooth and "tasty". Winthrop will then laugh and say he was kidding, but "had you going, didn't I?" The Chosen One and Harold had a similer conversation in Fallout 2.

Appearances
Many ghouls in Fallout 2, Fallout 3 and Fallout Tactics call the Player Character a smoothskin. Most likely the first you encounter in Fallout 3 is Gob in Megaton.