It's hard to get the take-me-not-serious tone. Just not taking the writing & production values seriously doesn't provide the tone. Most of the dialogues are horrible. Sample this supposedly funny line:
Our dear friend is banished to Earth! Loki sits on the throne of Asgard as our King! And all you have done is eat two boars, six pheasants a side of beef and drink two barrels of ale! Shame on you!
Shame indeed. This happens when Thor is getting to know the Earth people and their way of life: after gulping down a cup of coffee in a diner he smashes the cup asking for more. When he's politely reprimanded by the girlfriend that Earth people order in a more gentle way, he nods in an understanding manner. Wow! I've seen superhero movies where the guy comes to our planet and does funny things not knowing how stuff works. But this writing is scraping the bottom of the barrel. This is stuff rejected in a screen-writing convention in Peoria.
When Thor, the god of thunder is stripped of his superpowers and pushed down to Earth, he faces a giant robot sent to kill him. It slaps him and he falls down unconscious. His girlfriend swoops him and cries not knowing if he's still alive. And at this moment, allow me to remark on the range of expressions she exhibits - played by Oscar winning Natalie Portman, she doesn't invest a quarter of the emotional sincerity expected of an actor for such a scene. She plays it like a high school drama and director knows that the audience know it's a tongue-in-cheek outing and doesn't bother to re-shoot the scene. This laxity, a sense "y'all here to chill" awareness on the part of creators works on a good script. But the script is fractured, childish, immature. Ironman nailed it in letting the viewer take a break in a charmingly intelligent way. With 'Thor', the break is a bit long, about 110 minutes.