MERKIN in the OED

[RonButters at AOL.COM]

I checked the OED online entry for MERKIN today for an exercise in my History
of English class and was puzzled as to why the definition that is given is
'artificial vagina'. The cites--from the delightful 1660 want-ad ("Lost in
Covent Garden, One Merkin") to the entry from the 1970s clearly indicate that
a MERKIN is hair, not simulated flesh.

Did they even have blow-up dolls in the 17th century?

I wonder how this happened--or am I missing something?