The Audubon Ballroom is an Anti-slavery Terrorist Organization consisting of escaped slaves.
In the Honorverse, slavery is based on genetic modification.
The planet Mesa, which is run by a collection of corporations, is the main supplier of genetically-modified slaves.
The main culprit is Manpower, Inc... which creates slaves for specific jobs by genetic manipulation and by behavioral programming (including torture & rape) "to instill correct attitudes and behaviors".
Most star nations are signatories of the "Cherwell Convention", which outlaws genetic slavery, but few really enforce the provisions.
The two main protagonist nations in the series, the People's Republic of Haven and The Star Kingdom of Manticore, despite being at war, do vigorously enforce it... to the point of applying the death penalty.
Manticore's Navy applies it even to the crews of ships "fitted with equipment for the slave trade"... whether there are slaves present or not!
Genetic slaves are tattood on their tongue with their type code... so the common greeting among slaves is to extend their tongue to show their coding.
The Ballroom has the nasty habit, when they have located someone involved in genetic slavery in any way, of sticking out their tongue at the offender, asking "Shall we Dance?", then killing the slime-ball!