I'm with Wysiwyg on this one. I learnt it in the 40s with the N word, and thought nothing of it at the time. My daughter learnt it as tigger (not tiger), and didn't know it had ever been different. I couldn't teach it the old way, but tigger seems too forced, tiger has a completely different rythmn, so I'd leave it alone.
But I'm with Nerd as well, if it is passed on by people who have never know it any other way, then thats fine.