Hard Elbow...
A man is in a hotel lobby. He wants to ask the clerk a question. As he turns to go to the front desk, he accidentally bumps into a woman beside him and as he does, his elbow goes into her breast. They are both quite startled.
The man turns to her and says, "Ma'am, if your heart is a soft as your breast, I know you'll forgive me."
She replies, "If your penis is as hard as your elbow, I'm in room 436.