One of the challenges is drink 5 things of rum, is it unlocked eventually in the story or something because I haven't found where you can.

Kenway drinks something when you go to a bar and ask for rumors. Try that 5 times.

Turn on the Kinect and buy a bottle of Captain Morgan's.

Admiral Nelson's is also acceptable.

Any pirate themed rum, really.

When you unlock a bar you have two options go up to the bar tender and pay him 200R to mark a location of a convoy or other secret on your map or usually to the right or left at the end of the counter will be a bottle of rum its easy to spot as its glowing. You should be able to click on the bottle and drink rum for I think 10R a drink.

There is also an achievement/trophy for drinking until you black out so when you do this for the Abstergo challenge keep drinking until you black out and you'll also get an achievement.

Awesome, thanks!

I am not sure what it says about the landscape of gaming discussion or myself when I read the topic title and thought "So what now, images of alcohol cunsumption in our entertainment will come into question?!" And then relieved when it was actually a gameplay related question.

Also, I need to try that.

There's a little bottle of rum at the taverns that you can pay 5 R to drink, i think you have to do the bar fight thing to unlock it though.