John Constantine has been written as a character that murdered his twin brother in the womb, pumped his body full of demons blood to fight cancer, made fools of representatives of both heaven and hell, and, perhaps most importantly, sang for a punk band in 1977. Fortunately, he is a man with baggage he can't seem to drop. All of these life events feed into Constantine's persona and come into play as he encounters new ordeals. The character has been re-invented many times through the over 20 year run of the Hellblazer series by re-interpreting the meaning of these memories in relation to whatever problem Constantine is currently trying to sort through.
Aside from setting up a traumatizing demon conjuring mishap at Newcastle, Constantine's role as singer for the fictional punk band 'Mucous Membrane' is a story often returned to in order to define his character as cautiously chaotic, as in Jason Aaron and Sean Gordon Murphy's beautiful run last year. A slightly different take on this history has been explored by several other teams, however, emphasizing other aspects of the diverse punk culture of the time.
In a 1995 issue from Paul Jenkins and Sean Phillips, they explore Constantine's friendship with some more 'Crass' inspired peace punks. In possibly the only story in which Constantine can be seen riding a bicycle, we find a touching work on his loss and recovery of a friend after a punk show at Edgewood. One night the friend bikes off into a time warp and goes missing for a couple of decades. In this panel, Constantine has found his friend displaced in time, and they ride against a medieval battle back towards the present. In the midst of this onslaught, he can only think of Hal David and Burt Bacharach's film score "Raindrops Keep Fallin' on my Head".