The pair have done so twice in the past week, and Tweeted pics of the results.
Last Tuesday, the pop star and the Glee actress dressed up "full-time fancy," in Swift's words, and went out with friends to dinner to celebrate Shirley MacLaine's 78th birthday.
"Had a long day & don't know what to celebrate later...? Because you need a moment to be young? Find your moments," Agron wrote after posting the photos.
They apparently had fun, because this weekend they celebrated Agron's 26th birthday with a blowout circus-themed costume party, which Swift, 22, deemed to be "the most magical night."
Swift's birthday isn't until December, so it remains to be seen how they'll keep this particular passion going.
Courtesy Dianna Agron