They're not even good for that! They are too small and stiff for TP, and don't even burn particularly well.
I can remember being in Bolivia right after their hyperinflation in the later 1980's, and old paper money was still littering the fields and ditches --- it was a sight to see! People apparently just cast it to the winds after a certain point. Guys were selling thick bundles of 100,000 peso notes for maybe 50 cents as curiosities. My disgust at what their government had inflicted on them kept me from buying any, though.