"They gave it me," Humpty Dumpty continued thoughtfully, as he crossed one knee over the other and clasped his hands round it, "they gave it me⸺for an un-birthday present." / "I beg your pardon?" Alice said with a puzzled air." / "I'm not offended," said Humpty Dumpty. / "I mean, what is an un-birthday present?" / "A present given when it isn't your birthday, of course."
Source: wiktionary