Last night, I watched My Name Is Earl on NBC. It was a rerun episode from 2008 titled "Joy in a Bubble."
I will not describe the plot because I was not paying much attention to the show. (I was reading with the television on in the background waiting for The Office and 30 Rock to come on.)
The show did get my attention when Earl's sons attended a young boy's birthday party. When it was time to blow out the candles on the birthday cake, the birthday boy wished aloud, "I wish I was a girl!"
It was the birthday boy's only appearance in the episode (he is not a continuing character in the series) and there was no trans theme in this episode. So, my guess it was a throwaway line intended to get a laugh from the audience, but I am sure it was not a joke to any trans-woman watching the show.
I don't believe I ever made a wish to be a girl when blowing out the candles of my birthday cake, but I do recall on more than one occasion going to bed and hoping I'd wake up female.