Zoe (Jennifer Lopez) has given up on finding the man of her dreams and decides to become a single mother and undergoes artificial insemination. The same day she meets Stan (Alex O'Loughlin) when they both try to hail the same taxi. They run into each other twice more at a farmers market and a pet store. Stan convinces Zoe to go on a no-obligations date. Zoe is still uncertain whether she is pregnant or not and if she should tell Stan. The night she takes the test, Stan takes her for a romantic dinner in a garden. Things don't turn out as well as planned when he spills the wine and a fire occurs. At the end of the night Stan asks her to come to his farm during the weekend and Zoe finds out that she is pregnant.
She goes to the farm determined to tell him that she is pregnant. They have sex and afterwards Stan is confused and angry that she didn't tell him before and Zoe leaves the next morning believing that things are over between them. However, Stan decides he still wants to be with her and they reconcile. They go to the doctor and find out that Zoe is actually carrying twins. Overwhelmed, Stan goes to a children's playing area to figure out what it means to be a father, but is suspected to be a pervert; this is soon cleared up. He finds a friend there that he can talk to about the pregnancy throughout the movie, while Zoe gets little support from her Single Mothers and Proud group when the group members discover she is no longer single. Stan takes the next step to becoming a father and orders a stroller for the twins. After many misunderstandings and comedic revelations, Zoe and Stan are walking into the Market when they run into Stan's ex-girlfriend. Due to Stan's remark that the twins are not his, Zoe believes that he is not ready to become a father to them, and breaks off the relationship.
Later, the stroller that Stan ordered arrives and Zoe figures out that Stan was never planning to leave. At her grandmother's wedding, Zoe's water breaks and on the way to the hospital they make a pit stop at the Market. Zoe apologizes to Stan and they begin to work things out. He pulls out the penny that she turned over when they first met and Zoe promises to trust him more. Zoe gives birth to twin girls, one of whom they name Penny. In the end, Stan opens a store/restaurant next to Zoe's pet shop and after the Grand Opening speech Stan asks Zoe to marry him and she says yes. On their way home, she spontaneously throws up into a rubbish bin and realizes that she may be yet again pregnant.

Question: What does Stan keep as a memento?
Answer: He keeps a penny.
Alternative answer: A penny.