The blonde singer/actress has been romantically linked to Cook for months, but insists the two EMPLOYEE OF THE MONTH co-stars are just good friends.
But, to further fuel rumours, Simpson has asked Cook to be her sidekick at the Teen Choice Awards on 20 August (06).
Defending her decision, Simpson says, "I'm glad I'm doing it with Dane because he's used to the stage.
"I will be messing up, I'm sure, many times, but he's good at making it a good thing."
And she preempts the romance rumours, stating, "Dane and I are very good friends... He's an awesome guy. He's in Vancouver shooting a movie right now. We talk a lot, but I'm not dating anybody."