Scrappy

Wow, you're really in a bad mood. Don't get scrappy.

Google was once small and scrappy.

That was a scrappy lecture.

He's a scrappy dog and will charge at you if you taunt him.

In those days PGS [Portsmouth Grammar School] was full of sadistic staff and scrappy boys called things like Smudger, Muzz and Titch.

The [Washington] Post's proprietor through those turbulent [Watergate] days, Katharine Graham, held a double place in Washington’s hierarchy: at once regal Georgetown hostess and scrappy newshound, ready to hold the establishment to account.