Both wishes were granted, but since they were spoken at the same time, the result was that they were switched as if they were spoken as:
Jon said "I wish my hair was dyed red."
And ...
Karyn said "I wish that you would be content with having double D breasts."
The stone flashed and the wishes were granted.
"Oh my god, Jon!" Karyn said, shocked by Jon's appearance.
But Jon was fine with it. He was a little upset with his hair being dyed, but he was perfectly content with his double D breasts.