s/^/,$"@m.\n\n@m,$"@z.\n\u@_/,/s/until/99/*split@m=(@z=(++$n,bottle.$&,of,beer),on,the,wall),/\n+/?take7one7down7and7pass7it7around:go7to7the7store7and7buy7some7more;print$'.$`
# or
s/^/,$"@m.\n\n@m,$"@z.\n\u@_/until/99/*split@m=(@z=(++$n,bottle."s"x/\n+/,of,beer),on,the,wall),$&?take7one7down7and7pass7it7around:go7to7the7store7and7buy7some7more;print$'.$`