"For a hundred bucks" joke

A guy goes over to his friend's house, rings the bell, and the wife answers.
"Hi, is Tony home?"
"No, he went to the store."
"Well, you mind if I wait?"
"No, come in."
They sit down and the friend says, "You know Nora, you have the greatest breasts I have ever seen. I'd give you a hundred bucks if I could just see one."
Nora thinks about this for a second and figures what the hell - a hundred bucks. She opens her robe and shows one. He promptly thanks her and throws a hundred bucks on the table.
They sit there a while longer and Chris says, "They are so beautiful I've got to see the both of them. I'll give you
another hundred bucks if I could just see the both of them together."
Nora thinks about this and thinks what the hell, opens her robe, and gives Chris a nice long look. Chris thanks her, throws another hundred bucks on the table, and then says he can't wait
any longer and leaves.
A while later Tony arrives home and his wife says, "You know, your weird friend Chris came over."
Tony thinks about this for a second and says "Well did he drop off the 200 bucks he owes me?"