Some might say it is a "Smart" comedy. Meaning you need to be smart to "Get it".

And if you don't get it, you aren't that smart.

I remember one scene, Sheldon and Leonard are playing a game of chess on one of those 3-D Star-Trek type Chess boards. In it, Leonard hesitates on his move for a while, then finally moves. Sheldon moves quickly, calls "Checkmate". And the joke is then he says "It must be humbling to suck on so many different levels." Then points to the board at different levels.

An instant classic. Watch for yourself.