Sports defined by one-on-one fighting, including boxing, wrestling, pancration, and the various martial arts;
including today, and most especially, the various forms of mixed martial arts, known sometimes as freefighting or "UFC-style" fighting.
In the ancient Greek and Roman world, three of these sports -- boxing, wrestling, and pancration -- were fought nude, and though not explicitly erotic, there was genital contact during the contests.
Many men into Frot are also involved in combat sports, and find fighting in general to be erotic.
Please note that those men are not necessarily into cock combat, but may seek a mildly combative element in their love-making.
Please note also that not all men into Frot are also into fighting; some are, and some are not.
For a discussion of nude combat sports in the ancient world, see Xystarchy.
For a discussion of modern fight sport, see The Warrior Male and related articles.
See also natural male sex aggression.