Once I had a secret love
She wore a nylon negligee
When our night of love was done
She said I did not have to pay
When I asked her why her love was free
She said, "Sealy Mattress sponsored me
Last night we were on channel four"
Now my secret love's no secret any more

Remembered from early teen years, circa 1960. I think it was on an LP by an Ivy League glee club.