Pass the salt...
Here's one way to get our 3 pounds of gray matter to wrap around the scale of the Cosmos. With the grains of ordinary table salt representing the stars.
Take a box of salt and pour the contents into your free hand until it fills up your palm. That's about 10,000 grains of salt right there.
Now to equal the amount of stars in the Milky Way galaxy, about 400 billion. You would need over 10,000 boxes of salt, which would fill up an ordinary size classroom to the ceiling and spill out the windows.
Remember the pot scene in Animal House?