Have you ever done this? What are some tips you can offer? I have noticed an unusually homoerotic culture in poor neighborhoods, where the guns are cheap and the cocks are large. There is a certain amount of risk involved, you never know whos 'packing' literally and might be extremely offended by your proposal for a mutual semen disposal. I think many guys in the ghetto would be willing to do something sexual for a certain amount of money, maybe 20-50, 100 or more if you look strange. I have seen many videos of 'str8' guys who look really hoodish getting BJs on cam from creepers so who knows how it really works.
I think possibly driving around late-ish and trying to spot one on the street might work well, but police might think you are just trying to pick up a hooker as opposed to trying your luck with a trick.
Maybe leaving a trail of quarters on the ground leading to bushes might work?