I could have told him that in person, but why bother

Dear anonymous guy,

I realize that few things suck more for a cyclist than having another person tie their bike not only to the shared lamp post, but also to your bike.
I could understand the need for petty revenge by also tying their bike up and going home, even though I don't really think it necessary. After all, with the post being right next to a huge cinema and the law school (i.e. lots of bike at any time of the day), chances are, that it really was an accident.
But do you really think that tying up the bike and leaving a note with your phone number serves any purpose but creating more work for you? It's you who's getting a call in the middle of the night and has to walk back into the city instead of checking tomorrow on your own time.

Regards,
the person who just had to wait 20 completely unnecessary minutes (and I am really sorry. I've got nothing against you or your bike, but with those hundreds of bikes at that place, things like that just happen)

P.S. Not that you will care, but this actually helped me to calm down after the suckyness that was The Exorcism of Emily Rose