This is a rude ballad that probably dates from the early 18th century. It was featured in a BBC TV documentary that was first broadcast June 14, 2010, A History Most Satirical, Bawdy, Lewd and Offensive, which was episode 1 of the short Rude Britannia series.
When it is revealed that the song is sung to a young man by a comely wench, there is no need to ask what she is asking him to put in, and where she is asking him to put it.
Professor Tim Hitchcock said some of the ballads sung on the streets of London at the time were embarrassing, they were so absolutely explicit. None more so than this one, which was performed in the programme by Lucie Skeaping.
Also known as "A Young Man And A Maid", it appeared in volume 6 of Pills To Purge Melancholy which was published in 1720.
Suggestion credit: Alexander Baron - London, England, for above 2