The guardians of the galaxy!
or
Because it would fall over if it lifted the other one.
or
At the crystal ball.
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It's not a shrub, it's a lemon tree my dear Watson.
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Mt Rushmore. They're a rock group.. it's a rock...group
or
Twenty. One to hold the bulb, two to turn the ladder, and 17 to be on the guest list.
or