Not happened to me and to be honest never thought about it. Defo wouldnt offer a ciggerette. I love spurges random threads.

front to back has happened once or twice, but front to front, never.

As awkward as this sounds, I put my hands on someone elses hips if I'm worried about it.  That way one of us is in control of how close we are and it isn't accidental seen as intentional.  It'll either be intentional or it won't happen.

That said, it's really tough to do Spurg.  In fact, you'd have to thrust your package into someone in order to do it.  The physical characteristics of most males and females makes us either top heavy, or gut heavy.  You'd have to be pushed or grab hold of a guy and pull him into you for you to bump uglies.  Unless of course you both are so well endowed that your huge packages extend several inches beyond your frame.

To honestly be so concerned about this that you post about makes me think you secretly want to, just to figure out what it'd be like to feel another mans cock against your own, even if it were only between denim. 

Have I ever accidenly bumped the junk with another male? No. What would I do? Depends on the reaction of the other male. Could result in a mutual "excuse me", could result in a fight, could result in more bumping.

The fun is all in trying to make it appear as though it were not intentional.

I would pretend like nothing ever happened and quickly keep walking just so that I don't make the situation even more awkward.

Do you repent and/or have sex with a woman immediately afterwards? If not, you're going to Hell forever.

that's why I love busy tubes/undergrounds