Potential Reality

Little Johnny came home from school and asked his dad to help him with his homework. He had to find out the difference between 'potential' and 'reality'.
Johnny's dad says, "Go ask your sister if she'll have sex with the trash collector for a million bucks!".
"I can't ask her that!," exclaims Johnny 
"Just go and do it!", his old man insists.
Johnny comes back a few minutes later, wide eyed," She said YES dad!"
"Now, go ask your mother if she'll have sex with the trash collector for a million bucks!" 
"I can't ask Mom that!", says little Johnny. 
"Just do it!!!", snaps his father.
Johnny disappears and returns even more amazed, "She says YES, anytime!". 
His father smiles, "Now, go and ask your brother if he'll have sex with the garbo for a million bucks!".
Little Johnny asks his brother, and returns, "Geez Dad! He said yes too!".
"Well, now you see the difference son", explains his father.
"You see, 'potentially' we have three million dollars in this family, but in 'reality' we have two sluts and a fag!!