This is a story related achievement
You get it for rescuing Rebecca for the 1st time from the twins.
You fight both the twins at once and they are both armed with a sword,and can take you down quite quickly if they both corner you. Luckily you only need to beat one of them for the fight to end, so concentrate your attacks on the 1 twin.
There is pleanty of alcohol around to top up your health but if your going for the no meat,dairy,alcohol cheeve you might want to stock up on 2-3 OJ's or juices.
The fight takes place in shoal nightclub so if ur mission marker leads you there and your low on health or consumables, stock up.
** Snapping a shot of one of the twins when they pose and you get the bonus PP symbol above their head will net you over 1000 PP erotic for the Adult content achievement.
**Ninja mask is outside the club behind the checkout desk in lobby on a hat stand, once picked up it will unlock in your locker, if u die during the fight you will need to pick it up again.