The People of Gibraltar (site) wrote about this rhyme:

"One could easily mistake the above for a nonsense verse but in fact it was simply a horribly mangled version of a Scottish jingle which begins as follows:

'Sandy sandy waters
Waters of the Dee'

As for the 'gu saniguera' one can only assume it had something to do with heather."

If anyone knows more about this rhyme or if you know the Scottish rhyme "Sandy, Sandy Waters" (could it be a version of "Little Sally Waters"/"Little Sally Sander"?) - please email me. Thanks! Mama Lisa

Thanks and Acknowledgements

Thanks to Paul Schoneveld for sharing this rhyme. The rhyme can be found on the site The People of Gibraltar.