A similar variation is: "He's not the sharpest knife in the drawer" or "He's not the sharpest tool in the shed". When a person is described as being "sharp", it implies that they are clever, observant and quick-thinking. So, it's quite popular to play on words involving objects which are sharp, like knives and tools, to convey that someone is perhaps a bit slow or dim-witted compared to others.

"Tackar" is a slightly more formal way of saying "tack (så mycket)". It isn't used as a greeting as such, just to show appreciation. I've never heard anyone say "jag tackar dig", but sometimes people say "tack ska du ha", which is even more formal than "tackar".

"Crest" is used to describe the high point of a wave, whereas "peak" is used to describe the high point of a mountain. "Peak" can also be used to describe the point when something is at maximum intensity or development (i.e. "He reached his physical peak in his early twenties", "Sales usually peak during seasonal holidays").

Apropos of the horse meat scandal, I'd like to add that it's not at all taboo here in Sweden where it's sold on the supermarket shelves along with reindeer and moose meat!

 

I'd say that dissing Astrid Lindgren (author of Pippi Longstocking) is highly taboo in Sweden.

Ah okay. As I mentioned below, I would say that as a rule of thumb you can use definite article with strangers when referring to things which everyone are familiar with.

From the explanations below, it sounds like this phrase only applies to females. Can it be used when describing men as well? (Since you wrote "he").