Hubble bubble toil and trouble
Fire burn and cauldron bubble.
Everyone knows that quote from...well, somewhere or other.
(It's not, I'm afraid, from Macbeth: the Macbeth witches' cauldron goes double double. No, really, it does. In Act IV, Scene 1. Look for yourself if you don't believe me.)
Right, having got that one out the way, a hubble-bubble is usually a water-pipe or hookah:
Photo by Sergei Mikhailovich Prokudin-Gorskii
But if you can't find one of those - and I can't say they're too common here in Southern England - then a hubble-bubble is also a hubbub or a turmoil.
Well, they're common enough almost everywhere. Try any school gate, shop with a sale on, or pub at throwing-out time, and there you are.
Bus and railway stations in the rush hour are good for hubble-bubbles, too.
If you live in the Gobi Desert, or somewhere else where it's not easy to find two people to rub together, then a hubble-bubble can also be a gurgling sound.
I can only suggest in this case that you either eat lots of ripe fruit, or buy some mouth wash.
Spot the frippet: hubble-bubble. This word was made up for fun in the 1600s to make bubble sound even funnier.