It was established in season 3, episode 18 "Leap Year" that Sue's birthday is February 29 (although the show has repeatedly mishandled this). She couldn't kiss the dragon on her 21st birthday because there wouldn't be a February 29 that year.
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The named of this episode is called Toasted season 9 episode 15 The Middle tv show series Frankie takes Sue to the bar to celebrate her 21st birthday # ...
Things don't go as smoothly as planned for the Hecks when Frankie helps Sue celebrate her 21st birthday by taking her to a bar close to the college; M…