I used to have this cartoon, but that was on another computer, long ago and far, far away. I think it ran in Playboy about 35 years ago. If anyone can tell me where to download it, I'll send you lots of kisses!
It's a one-panel cartoon. A cute 12-year-old girl in pigtails and a pinafore is sitting on the edge of the bed (evidently in her bedroom), smiling. Her mother is sitting beside the bed in a chair. The mother is saying, "We need to talk about your future, John."
I did a google search for "transgender cartoon," but the stuff I found was pretty bad. Lots of cliches. (I actually saw two cartoons, by different cartoonists, in which "cross-dressing" meant "dressing up to look like a cross." Ugh.)
*** Jenna ***