One prisoner I worked with was a long-term heroin addict. He told me that nearly every beggar in Norwich was an addict, and the moment I handed one a few bob, he'd be off to get a 'wrap' (ie heroin in a paper twist). He knew most of them personally and thought I was an absolute twit to give them anything! I have in the past handed one a sandwich and a hot coffee, but he didn't look too delighted with that, so maybe the inmate was right. (By the way, his words were a bit stronger than 'absolute twit'!)