I also have heard Squirrel, the first time I ever heard of SQL. It was in a webinar info session for just a very superficial top-level type of understanding, really intended for nothing more than to acquaint first-tier support staff with technical terms and concepts. "SQL stands for Structured Query Language. For short, we can call it 'sequel' or 'squirrel'." (Cue stupid clip-art graphic of a buck-toothed smiling squirrel on a tree branch, holding an acorn, because what's a webinar without insipid mnemonics?) That sort of thing.

I grokked the use of 'sequel', because the letter sequence S-Q-L is exactly that word, sans vowels, and even if schwas are substituted for the vowels, the pronunciation doesn't change much.

But for 'squirrel' I had to imagine that they were taking the R from 'queRy' and injecting it to make SQL into SQrL for the sake of a cute memory device that would resonate with people who weren't expected to have any interest deeper than a front-line customer service drone.