1. Wife collects dick pics. Husband feels concerned and she says that to try and assuage his fears. She means that just cause they are sending her pics, doesn’t mean they are promises of anything more
2. Fantasy story: Hero has to call in ask a favor from a dark queen. He promises to return the favor and that’s when she says the line and follows it with “a promise is easily broken but a penis is…harder.” So if he wants the favor he’s got to fuck her.
3. Teasing/humiliation: mistress gets her sub hard and then teases him with what he thinks he can do with that erection. So the line in this case means “just cause you have a hard cock doesn’t mean it can cash the checks you’re signing”
