This is not exactly a joke but a sabotage or a revenge.

There is a legend handed on by the bus drivers of my city, the legend of the maron glacè: Someone had the sly idea to refrigerate his turds, adorn each one of them with a red ribbon and hide it on a bus in the depot...
When the turd is refrigerated it doesn't smell, but things changes after a while... when the bus is on the road   ... The author of this joke is unknown and there are known variation like the "yellow icycle"....

You bus drivers are crazy people...
I have heard of this being done over here as well.
There is a variation on this side of the ocean where you take a small
paper bad and put a healthy amount of dog poop into it.
Next, you go to someone's front door and just before you ring the doorbell
or knock on the door, you set fire to the paper bag.
The "victim" answers the door, and noticing that there is a small fire on the
doorstep, proceeds to stomp out the fire with his/her foot, getting the stinky
dog poop all over their foot, while putting out the paper bag fire.

We're just as crazy here as well.

Here's one you might try when over at a friend's place and is most effective
after several beers are consumed.
Put clear plastic cling wrap (used for sandwiches and for covering food in bowls),
over the toilet bowl. If done correctly, the victim won't notice and when he starts
to have his leak, he will pee all over the place. It might be best to leave
your friend's place, or he will make you clean up the mess.

Thi is really, really bad  

Really bad, eh ?
Sure, sure...
You probably can't wait to find victims to see what happens...

Hey, Den. We used to do the old cling-wrap on the bowl trick in Army Cadets as a kid. We'd sneak into the other school's cadet barricks on the anual retreat and cover all their toilets... or sneak into their open tents and hide raw eggs under their pillows