A state of intestinal disorder, usually accompanied by a rumbling stomach; for example, 'butterflies in the stomach'.
The origin isn't known for certain.
Colly is an English dialect word meaning coal dust. Blackbirds were hence known as colly birds. The song Twelve days of Christmas is usually sung as 'my true love sent to me, four calling birds'... but the actual line is 'four colly birds'. Colly-wobbles could have derived from indisposition caused by breathing coal dust.
It is more likely that this is a nonsense word formed from colic and wobble. The earliest citation of it is from Pierce Egan's edition of Grose's Dictionary of the Vulgar Tongue, 1823:
"Collywobbles, the gripes."
The nonsense origin is supported by two other early references, clearly used with comic intent.
- Punch October 1841: "To keep him from getting the collywobbles in his pandenoodles."
- Cuthbert Bede The Adventures of Mister Verdant Green, 1853: "A touch of the mulligrubs in your collywobbles?"