What the meaning of "doodling around" in The Big Bang Theory ?Can you guys help me?
from first episode of the first season.The whole sentence is "Sheldon: Yeah, well, it’s just some quantum mechanics, a little string theory doodling around the edges. That part there, that’s just a joke, it’s a spoof of the Bourne-Oppenheimer approximation."

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Doodling around always means drawing without much thought.  The joke is that the hardest math problems there are - is nothing but playing with a pen to this character.  This is the only way to understand doodling in this context.

Answer

= fritter away time

http://www.thefreedictionary.com/doodle