Charmed by Will Shortz's collection, in the last Word Ways, of original riddles based on spoonerisms, I whacked my writs to come up with a durther fuzzin' examples, and beer's the hunch.
"More Spoonerism Riddles,"
Word Ways: Vol. 44
, Article 23.
Available at: http://digitalcommons.butler.edu/wordways/vol44/iss2/23