Black Rifle Disease is an illness that afflicts thousands of people. Treatment is costly, running from the hundreds to the thousands of dollars per dose.
Traditionally, BRD causes a desire or lust for AR15 pattern rifles, but often mutates into a desire for other semi-auto magazine fed rifles, including AK's, FALs, H&K's (you suck, we hate you), M1A's, Bullpup's, and more.
BRD is so wide spread support groups even have their own forums, such as arfcom, falfiles, m4carbine, and even HKPro (because they really do hate you).
I treat my disease from time to time, sometimes with large doses (entire rifles), but most often with parts and accessories. The AR15 sub-strain is perhaps the most devious. Parts accumulate over time, and before you know it another AR is in your possession. That's where my trunk gun came from.