As a BT Customer, I can assure you that it stands for "Bloody Terrible", and the buyout is only feasible because the telecomms regulator is as toothless as a wet cabbage.
My friends who use it, assure me that EE stands for "Extremely Expensive".
As an EE user I have to disagree. It actually stands for "Eencredibly Eencompetent."
As I discovered when they contacted me to suggest I go from Pay-As-You-Go to Pay-Monthly, on a plan that was actually financially advantageous. Only to find out the next time I was abroad, a week later, that there was no roaming activated on Pay-Monthly. I spent a week attempting to get through to customer service with no success ("We estimate we'll be with you in 1m", for an hour and a half). When I finally managed to get through to them back in the UK, they gleefully told me that roaming could only be activated on pay-monthly if you'd been with them for over a year (W... T.... F.....).
I calmly explained that it was *them* that had contacted me to switch plans, when I'd been using the roaming facility on my PAYG for a week out of every month in the past year, so could they kindly get their thumbs out of their arses and fix it or cancel my plan entirely. And suddenly it wasn't so much of a problem to instantly activate my roaming.
Why am I still with them? Best coverage in the UK and abroad, and best prices for my (very non-average, admittedly) usage pattern. But holy shit, are they ever incompetent.