Just win a match vs. the player with a bounty, if it's not yet claimed.
it'll tell you in chat that you got it
"Playername has claimed $$$ a bounty on Playername2"
it'll tell you in chat that you got it
"Playername has claimed $$$ a bounty on Playername2"
The past makes you wanna die out of regret, and future makes you depressed out of anxiety. So by elimination, the present is likely the happiest time.
Kill and earn, here you can find all recent bounties, not many at the moment though: http://forum.toribash.com/tori_bounty.php