BB gun is in the lead by 10 votes and you've had a full day to handle it
The forums has spoken
Peg the pusillanimous individual
Don't feel bad. Odds are if it's a street cat it's a little tougher than most. It's coat will take some of the impact, and everything else will kinda just be a "me-owch" moment. Cat won't die so long as you don't aim for the face or back door.
Bonus points +50 if you hit cat balls in the process.
Or, y'know, you could let your cat starve, like half of the sarcastic posters on here have suggested.