that is a legit problem that people that abuse ... I think it is called caverject, andyway, that's what they get. also if you inject coke into your dick this supposedly happens.
also od'ing on trazadone.
there is an official term for it.
but "perpetual rock hard cock" will do for now.
if it turns black and blue or starts to hurt real bad, then the hospital gets involved and the solution isn't pretty.