You’re friend wasn’t the first to make such a mistake. There’s a poem from 1841 by Robert Browning, called Pippa Passes, in which he misunderstands the meaning of the word “twat.” Apparently he thought it was the name for part of a nun’s outfit.

But at night, brother howlet, over the woods,
Toll the world to thy chantry;
Sing to the bats’ sleek sisterhoods
Full complines with gallantry:
Then, owls and bats,
Cowls and twats,
Monks and nuns, in a cloister’s moods,
Adjourn to the oak-stump pantry!