Straight edge (sometimes abbreviated sXe or signified by XXX or X) is a subculture of hardcore punk whose adherents refrain from using alcohol, tobacco, and other recreational drugs, in reaction to the excesses of punk subculture. For some, this extends to refraining from engaging in promiscuous sex, to following a vegetarian or vegan diet, and to not using caffeine or prescription drugs. The term straight edge was adopted from the 1981 song "Straight Edge" by the hardcore punk band Minor Threat.