It aint a folk song, other than in the Louis Armstrong definition, but Bing Crosby had a song called 'Whistler's Mother-in-law'

If you're whistling cos your happy,
Be very careful pappy,
No telling just what a whistler's mother-in-law might do,
Although Momma's around the kitchen,
Attending to her stitching,
There's Granny behind the door keeping an eye on you!

She's got a direct suspicion,
You aim to do some fishin',
You're whistling I declare, gave it away for sure,
Well I reckon you might have known it.
Might just as well postpone it,
You aint going to go nowhere 'cept on a lecture tour

(Female voice off)
John, John, hear what I'm a calling,
Hurry up and mow that lawn,
(Bing) I mowed it yesterday!
(F.V.O)
John/ John, I'm not only bawling,
This old lady's up to something sure as your born.

Just you listen to Granny cackle,
She's found your fishing tackle,
A whistle for all your plans, now for the bad news too,
Look at Granny, She's got the flivver,
She's heading for the river,
Well isn't that like a man's mother-in-law for you!

If that isn't evidence of a mis-spent childhood, I don't know what is!

FC