What is a Bull?
A Bull is a man who has sex with another mans wife or girlfriend.
Originally in the context of the Hotwife and Cuckolding scene a Bull wss usually a Fertile male used to impregnate a Hotwife.
A White Hotwife using a Big Black Bull to get pregnant is the ultimate level of being a Hotwife, bringing total humiliation on her Cuckold.
These days the single guy in a Cuckolding relationship is reffered to as a Bull.
The Bull is there to perform a function: He has to sexually satisfy the Hotwife and often Humiliate the Cuckold.
If you are invited to perform the duties as a Bull check with the couple to find out exactly what they expect from you. Not all Cuckolding Couples have the same fantasies.