While Farming the Drop It! Achievement, I noticed that killing players allows you to pick up their seaforium, even cross-faction.
What it is: Griefing your own faction (Very fun in my opinion)
Why: Gain your fellow mans mistrust and give the attackers tons of honor.
How To:
1. Kill an attacking player with seaforium while defending.
2. Right click the barrel quickly! It disappears.
3. Plant it on your own gate (Preferably the one with the titan relic, if you get enough you can down it early and a SS Rogue or Feral Druid can cap it even if no walls have fallen).
4. Profit! This essetially allows you to win the BG for the opposite faction.