A particularly nasty, crusty, fast advancing rash or skin eruption. For some reason it appears to strike only chrome-plated, 360 degree assholes, while leaving the virtuous unscathed. By so doing, it restores ones faith in the mysteries of life.
Alarmed Fellow:"Don't sit in that chair---Mayson just got up from there, and he has the galloping crud!"
Unconcerned Grand Guy:"Don't worry--Mayson's a dirt-bag, but I have my aura of righteousness to protect me."