Little Johnny : 2+2+2=7...

Teacher: If I gave you 2 cats and another 2 cats and another 2, how
many will you have?

Johnny: Seven, Sir.
Teacher: No, listen carefully... If I gave you 2 cats, and another 2
cats and another 2, how many will you have?
Johnny: Seven, Sir.
Teacher: Let me put it to you differently. If I gave you 2 apples,
and another 2 apples and another 2, how many would you have?
Johnny: Six.
Teacher: Good. Now if I gave you 2 cats, and another 2 cats and
another 2, how many would you have?
Johnny: Seven!!! SIR!

A very angry Teacher: Where in the hell do you get seven from?!?!?
A very angry Johnny: Because,.... I've already got a fuckin' cat!!!