Webster defines a donkey's vagina as a vajonkadonk.

We got a country song in at work today called “Honky Tonk Badonkadonk”. They had to spell Badonkadonk phonetically (\ba-dônk-‘a-dônk\) and give a definition it on the cover of the single, but color me impressed, that’s fun. I'm sure it's better in theory; I opted not to listen to the actual song so it could stay pure and good in my mind forever.