What is a degrader?
A degrader (degradation giver) uses humiliation and degradation to embarrass their submissive. This is done in a consensual way, knowing that the degradation receiver finds it sexually arousing. It is not something every submissive will enjoy and needs lots of conversations around levels and boundaries.
Degradation givers are usually Dominants in a relationship and get a thrill out of the intense submission from the degradation receiver who does anything to make his or her dominant happy, even (and especially) if they have to humiliate or embarrass themselves in the process.
How to use humiliation and degradation in BDSM
Humiliation can come in many ways, some degradation givers might like to do it verbally with sexual slurs, insults and belittlement. Many male identifying submissive like to have the size of their penis ridiculed. This can also be part of a cuckold fetish. They may choose to degrade their submissive by urinating or ejaculating on them. Also they may command the degradation receiver to do something embarrassing for them or in front of others. Taking off clothing or flashing for example. They may lead their submissive around on a lead or use them as a footstool.