Great concept: print the lyrics to the lullaby on your kid's sleepsack, so you won't be at a loss for soothing music when you so desperately need it.
So far so good: it's got the second through fourth verses. That's what always trips you up anyway; it's not a question of not knowing the song, but of running out of words. Or maybe put a playlist on there, in case you draw a blank.
And it's true, I definitely don't know the words to "Der Mond ist aufgegangen," so this would come in handy. But what if I don't want to sing to the kid about the inevitability of death? Do they take requests?
Baby sleeping bag with screenprinted Songtext, EUR30 + shipping [dieszeuglich-info.de via notcot.org]