Rebellious or a reference to Belgian culture? (http://en.wikipedia.org/wiki/Manneken_Pis)

I never took them as such, but could be!

I think even worse are the ones that show Calvin praying to a cross. Talk about out of character…

Some of them are sort of funny, but others don't come even close (imo): peeing on speed limit signs (amount of deaths due to speeding is not laughable), peeing on the police (sure some minority migh be assholes but the majority I have met really do want to help people - and yeah they also enforce speed limits which, even though I completely understand how nice it feels to go insanely fast, are there for a reason) etc.

I most commonly see them on cars with aftermarket modifications (tuning cars), which is in line with your speed limit/police hatred connection.

And my favorite from a few years back - peeing on bin Laden.