Someone who wants to get stuck in to something new, but often goes wrong due to a lack of experience. Alternatively, those already involved may fear the enthusiasm and nerve of the 'Keeno' and try to curb this quality.
Essentially someone who is noticeably enthusiastic, sometimes erroneously, sometimes excessively.
That guy is such a Keeno.
Yeah, totally - he just won't stop trying.
He should just chill out and relax, go with the flow.
Yeah, too right. Though sometimes, I wish I'd done more when I had the chance.