Do you spank the wool, or wank the spool?
Another case of a spoonerism that does not qualify as a contrepèterie.
First of all, the pronunciation does not quite work:
spæŋk > wɑŋk (this one could be overcome by regional pronunciations)
wʊl > spul
Second, none of the phrases stand on their own as being either innocent, or funny once converted.
Third, it is wasting 2 phrases for the sake of saying “wank”.
Lastly, it just does not make sense: what can “wank the spool” possibly mean? If anything “spanking the wool” could be seen as the naughty part of the sentence.