v='Twelve drummers drumm0Eleven pipers pip0Ten lords a-leap0Nine ladies danc0Eight maids a-milk0Seven swans a-swimm0Six geese a-lay0Five golden rings0Four calling birds0Three French hens0Two turtle doves0twelf0eleven0ten0nin0eigh0seven0six0fif0four0third0second0first'.split(0)
for(i=12;j=i--;p(i-11?'And a':'A','partridge in a pear tree'+(i?'.':'!')),p())for((p=print)('On the',v[i+11]+(i<9?'th':''),'day of Christmas,\nmy true love sent to me');j<12;)p(v[j++-1]+(j<9?'ing,':','))
Note that non-ascii characters in the above source code will be escaped (such as \x9f).