Most commin road ones, speeding and skipping reds,
Its supposed to be a law to wait at the lights when it is flashing orange but no one ever does.

I would say using drugs. Except in Holland.

Generally Traffic speed, Underage drinkers, smoking, Age of concent. etc

underage smoking....like i do...in finland its VERY common....

Underage smoking/drinking/drugs.

Also speeding + tailgating.

I spose dad's most broken law is renting movies and then burning them. He doesnt sell them or anything just for all us to watch. Netflix ftw xD

This and vandalism, atleast around here in canada.

Speeding

It depends what you really class as speeding - cruising around a few mph over the limit isn't really speeding in my opinion.. The standard 'unwritten' rule is about 10% over the speed limit still being ok, and i'm yet to be pulled over for doing 35 in a 30 zone.

Round where i live there are so many cameras and all the little villages out in the country are so close together that people don't really break speed limits so much as bend them a little. It's too easy to get caught doing twice the speed limit and people hardly ever do go really over the top.

Pissing on the side of the highway >_>

I mean, when you GOTTA go, you just gotta.

Actual most ignored laws? (that's common, not some obscure thing like "no sex after 10")

Well I think going past stop signs, perhaps speeding when going past a yellow, burning rented media, porn? (I sure hope it's not really illegal....), piracy, not wearing a seatbelt, txting while driving, theft in school- that's not counting pencils and erasers :P...

Wow, there sure are a lot.