Me: a criminal?

I got a little reminder from the Police today. They reminded me to my great joy that I am indeed a criminal. Perhaps one of the worst kinds of criminal.
I have been found guilty of offensive behavior and for this must pay 800SEK to become a better person. I doubt this fine will make me a better person, in fact I'm pretty sure I'm kind of a pretty good person already.
Here is what I did: I was sitting with a couple of friends from work, having an after work beer on a Friday night, at a bar on the edge of Humlegården and after 2 beers I really had to go all of a sudden. So I jumped over the really low fence and went over to this huge tree and did my stuff. This is where the fun starts. I hear some shouting behind me as I'm getting ready to return to my friends: Three Police officers are jogging towards me with faces full of non-smiling.
They never shout at me, but for a really long time they stand around me saying stuff like "Didn't you know this was illegal"
, "What were you thinking", "We can't accept this as an ID" (my drivers licence had a crack in it) and "We'll have to wait here for a while" (They needed to call station to make sure I wasn't convicted of some other heavy crimes). All of the time these guys had the facial expressions saying "This is a very serious situation, we must be serious and
alert, this guy may be very dangerous".

All I could think about all this time was "NO: Don't say it!, NO: Don't start smiling, NO: Do NOT make a joke now, they will NOT appreciate it and will NOT think it is funny".

All in all I took up 30 minutes of three Police officers time on a Friday night because I peed on a tree in a park. A big tree, nobody could see my thingie ( the tree is located at GPS RT90 coordinate [X=6581868,Y= 1629082] b.t.w, pretty big huh :) ). Was this well spent tax money? Did I waste this tax money, or did they? I know they were wasted.

Where is the line drawn between silly and offensive?