Can I tickle them?

No.

Anyone with a good sense of humor know that Finns have an great sense of humor. It’s dark, dry, sarcastic, blunt, deadpan, and often immature. Finns’ upbringing is a recipe for superb comedic taste: little religious influence, everyone grew up broke, it’s dark and cold much of the year, people love to drink…all the elements are there.

Humor is very important to the Finns. It’s their defense mechanism for coping with the darkness, cold weather, and their own low self-esteem. A funny person is valued immensely. With all the long, awkward pauses in conversations with Finns, a good joke to lighten the mood is always appreciated.

But I’m Swedish or German, I have no sense of humor.

Nations with long lavish histories tend not to have good senses of humor. (With that logic, Ethiopians should be the funniest people in the world. And they are! Think about how many Ethiopian jokes you’ve heard.) But fear not, Sven – Finns are very polite and will laugh at almost anything out of politeness, especially if you’re a foreigner. Here’s a few topics to mention that’ll surely get Finns laughing…

Sweden – This is an easy one. Any lame joke about Sweden will KILL. Bonus: Add something about the Swedish army in there.
Finnish Cities – These jokes will never be understood by foreigners. But jokes about the nearly-identical town 50 kilometers away are a staple in Finnish comedy.
Well, anything Finland – Anyone with a good sense of humor knows all about self-deprecation, so the Finns love to make fun of themselves.
Russia and Estonia – See Sweden.
Race and sexual orientation – Go for it. Drop a racist joke in front of the CEO or on national television. No one cares. (with exception to all the foreigners in the room)
Poo and pee – Finns don’t consider themselves sophisticated people, so why not laugh at a good poop joke?

Any topics I should avoid?

Religion – Finns are the least religious people in the world, but religion is no laughing matter. Obviously God is Swedish or German.
Politics – Finns take politics very seriously, and with a dozen active political parties, chances are the person you’re talking to won’t agree with your political views. Plus high taxes aren’t funny.
Physical comedy – Finnish humor comes from within.
Swedish Finns – Especially if they’re around.
War and Independence – One of the few things Finns hold sacred.

…which topics am I missing?