2 friends live in the same apartment building. Their apartments are identical. One friend goes over to the other's. He sees that his friend painted his apartment.
"Wow I really like this, I think I'll do the same. How many cans of paint did you buy?" He asks.
"7" his friend responds.
The next day the guy goes to the store, buys 7 cans of paint and paints his apartment. When he's done he realizes he only used 3 cans. He calls his friend up.
"Hey man, I just painted my apartment but I only used 3 cans."
His buddy responds,
"Yeah me too."