A Limerick

[Baker, John]

        I've been wondering about this old limerick for years, and it occurred to me that the able membership of the ADS might know the answer.  This is from memory and originally from Harold Hart, Immortalia:  Limericks.

There was a lovely young miss
Who went down to the river to wash clothes
But a man in a punt
stuck an oar in her eye
And now she has to wear glasses

        I think I can work out the second and fourth lines, but for what word or phrase is the poem's closing a euphemism?

John Baker