zukkoi

cunning; sly; play unfair; foul

Word type: I-adjectives

Standard: ずるい

Standard kanji: 狡い

Example:

おい、おれが先にならんどってんで、入ってくるなよ。ずっこいなあ。
Hey, I was already lined-up here! Don't just cut in--that's not fair.

Commentary:

This word originally comes from ずるい, and is often used when kids are playing.
While this word sounds similar to すっこい, there are differences in meaning.