Scat is getting aroused by excrement, also known as coprophilia or scatology. Individual perceptions around scat vary greatly. Some guys are only interested in the visual aspects such as looking at an unflushed toilet or watching someone take a dump. Still others are into 'farming' or gathering shit from public toilets. Others smear shit on their bodies and some like to eat it.
Some find scat repulsive and off-limits, some find it repulsive but fascinating and for others it provides a bridge to the exploration of different kinds of BDSM. For other guys, scat represents a very sacred symbol of worship and devotion. Within Sado-Masochistic settings (S/M), scat can be used to reinforce the dominance of the Master.