Timebomb is a character in Fallout 3, and can be found inside Red's Clinic in Big Town. He is in a serious state and requires medical attention. With a Medicine skill of 40, you can revive him. Doing so nets you Good karma. You are rewarded with 5 caps if your speech skill is high enough. Upon completion of the quest Big Trouble in Big Town, you may receive Timebomb's Lucky 8 Ball.
If the player chooses to "put him out of his misery" a message will appear stating, "You coldly open an artery. Even to a skilled surgeon it will appear as if Timebomb died as a result of his wounds. You bastard." This will reward you with Evil karma.