Actually-- the topic of exactly what that phrase means has come up in discussions with members of other faiths that I have had too.
What it indicates to me is that God has a right hand and a left hand, and that Jesus sits to the right hand side of God the Father.
Some have told me that it meant that Jesus was on "the good side or in good graces with God" but they also insisted that they were one and the same being, and so not able to be physically "next to each other".
So then it flashed in my mind, the way that little boy in the joke took it (if trying to understand how God would sit on his OWN hand then.

-- but then I realized that it seems most who do not believe in the Godhead as three distinct persons-- accept the creeds and then probably don't believe there is ANY body with ANY body parts to *have* a hand.
Now me?? I am totally looking forward with longing for a warm hug from our Father in Heaven after I graduate from this boarding school called Earth!

Gramajane