Kill an enemy with the javelin from 80ft
How to: Since the javelin does impressive damage, it usually kills any target that is hurt from 80 ft. In bt_island, 80 ft is about from the Pirate booty area to the entrance of the cave where vikings come in. Of course, while in combat you can't measure it very accurately, so my suggestion is that if you see a crowded battle, take some steps back until you think it is like 90 ft away, start to charge the javelin by walking forward, and throw it at the battle when it's fully charged (remember the arc of the javelin).
Another good map is pvk_300_BoT_beta3. Charge up your javelin while running and then throw it into the knight's territory. With a little luck you'll get a kill.
Other tactic : Find an AFK person in an open area where you can get more than 80 ft away from him, make him bleeding profusely or about to be pushing daisies, and go finish him with the javelin. Of course this is for the unskilled people.