Snappy
Part of speech: adjective
Definition: rapid and without delay irritable Tidy; well-dressed; sharp.
Example sentence: I get snappy if I don't eat.
Rattling
Part of speech: adjective
Definition: lively, quick (speech, pace)
Part of speech: verb
Definition: Present participle of to rattle.
Example sentence: Scarily, football helmets, which do a fine job of protecting against scalp laceration and skull fracture, do little to prevent concussions and may even exacerbate them, since even as the brain is rattling around inside the skull, the head is rattling around inside the helmet.