According to Wikipedia, The Nightclub Two Step was initially developed by Buddy Schwimmer in the mid-1960s. The dance is also known as “Two Step”. It is frequently danced to mid-tempo ballads in 4/4 time that have a characteristic Quick-Quick-Slow beat. The dance position for Nightclub Two Step is with a more relaxed hold than typical ballroom dances. The leader rocks back on his left foot, the follower on her right, for one beat. A gentle but noticeable resistance is maintained during the rock step. Then both partners replace weight on the second part of the first beat. On the next beat, the leader takes a step to the left and the follower to the right. Then both partners repeat, but on opposite feet (the man rocks back on his right foot and moves to the right).
For an expanded definition of the NightClub Two Step, visit Wikipedia.